Regulation of idiotope expression. IV. Genetic linkage of two D region-dependent T15 idiotopes to the IgH allotype

The idiotopic (Id) repertoire of antibody response to phosphocholine was studied in mouse strains with different IgH allotypes. The T15 idiotype-bearing (T15+) serum antibody and antibody plaque-forming cells (PFC) were characterized with four monoclonal anti-Id that recognize distinct Id determinants on T15+ antibody encoded by VH-1 (of the S107 gene family), DH FL16.1, JH-1 and Vk22 germ-line genes. We have previously shown that expression of the Id designated AB1-2 and B36-82 depends on the third hypervariable loop (D region), whereas the other Id, MaId5-4 and B24-44, are influenced by VH structures outside of the D region. All four Id were expressed in the PC-response of all mouse strains tested, except the Ighj strains (C3H/HeJ, CBA/H-T6, PL/j), where the D region-dependent Id, AB1-2 and B36-82, were absent. The other Id, however, were normally expressed on individual PFC as well as the serum antibody of the Ighj strains. Expression of AB1-2 and B36-82 on 50% of PFC occurred in (BALB/c-Igha x C3H/HeJ-Ighj)F1 mice. The absence of Id correlated with a unique RFLP of the S107 gene family in Ighj strains. Finally, Id expression segregated with the appropriate RFLP pattern in individual (BALB/c x C3H/HeJ)F2 mice. These data demonstrate a selective genetic linkage of discrete T15 Id determinants, AB1-2 and B36-82 with the Igh allotype. By comparing these results with the available Ig sequences, we suggest that the Ighj allotype may be associated with an allelic form of the DH-FL16.1 segment which with VH-1, JH-1, and the Vk 22 code for the phosphocholine-specific antibody in the mouse.     

A study of autologous anti-idiotypic antibody-forming cells in mice of different ages and genetic backgrounds.

Antibody response to phosphorylcholine, an immunodominant epitope of Streptococcus pneumoniae R36a (Pn), is characterized by a public idiotype, T15, that is expressed on a large proportion of antibody molecules produced by all mouse inbred strains. The ability of the immune system to produce an autologous antibody to T15 upon immunization with Pn vaccine was investigated using a modified ELISA plaque assay for detection of single antibody-forming cells (AFC). The limit of ELISA assay for detection of specific anti-T15 AFC is approximately 300 cells/spleen. However, our studies failed to detect any autologous anti-T15 AFC in the course of the primary antibody response to Pn vaccine in young/adult (2-4 months) BALB/c and C57BL/6 mice. Aged mice (20-22 months) also failed to develop any specific auto-anti-T15 AFC upon the primary Pn immunization, despite the fact that the anti-Pn response in these animals changes both quantitatively and qualitatively. In order to generate specific anti-T15 AFC, BALB/c mice had to be immunized repeatedly with Pn vaccine (four weekly injections) or immunized directly with T15 protein in CFA. Different results were obtained with D1.LP mice that are low responders to Pn and express lower levels of T15 Id as compared to BALB/c. Young D1.LP mice produced high numbers of auto-anti-T15 AFC of both IgM and IgG isotypes following a single immunization with Pn vaccine. The kinetics of auto-anti-T15 response in D1.LP mice was similar to that of the antigen-specific response. These results demonstrate that the ability of the immune network to produce autologous antibody to a shared Id depends on the genetic makeup of the host, and that this response may be regulated by the level of Id expression.     

Rapid changes in the regulatory potential of autologous anti-idiotopic T cells during an antigen-driven primary response

The antibody response of C57BL/6 strain mice to Streptococcus pneumoniae R36a (Pn) is dominated by the T15 idiotype, but the responding cells appear to be idiotypically heterogeneous, in that individual antibody plaque-forming cells (PFC) may express some but not all idiotopes (Id) of the T15 complex. The presence of these distinct Id on the PFC was detected by a plaque-inhibition assay with three different monoclonal anti-Id antibodies, designated AB1-2, MaId5-4, and B36-82. A periodic change in the expression of AB1-2 and MaId5-4 Id was observed during primary (IgM) antibody response to Pn in the spleen. Those two Id were poorly expressed in the log phase of the response between day 2 and day 4 after immunization (few PFC in the spleen bore the Id), but they became detectable on the majority of PFC at the peak of the response, day 5 to day 7. The proportion of the Id-(AB1-2 or MaId5-4) positive PFC declined, again at day 10 after immunization. In contrast, the B36-82 Id was expressed on greater than or equal to 80% PFC throughout the entire primary response. The possibility that the apparent changes in the Pn-reactive cell populations are regulated by autologous anti-Id T cells was tested in vitro. Normal, unimmunized B cells were cultured with Pn, either alone or in the presence of syngeneic T cells isolated from the spleen of mice at the appropriate intervals after immunization: day 2 (T2), day 5 (T5), and days 10 to 14 (T10 to T14); T cells from unimmunized donors (T0) served as a control. The specific response after 4 days in culture was determined in regard to the total PFC as well as the proportion of PFC expressing the Id. Pn-stimulated B cells, alone or with the control T0 cells, produced moderate, variable levels of AB1-2+ and MaId5-4+ PFC. The expression of these two Id in the assay cultures was suppressed by addition of either T2 cells or T10-14 cells, but it was enhanced if T5 cells were added. However, these various T cell populations did not differ in their effect on the total PFC response. Also, the proportion of PFC bearing the third Id, B36-82 was high, and it was not consistently influenced by the added T cells.(ABSTRACT TRUNCATED AT 400 WORDS)     

The repertoire diversity and magnitude of antibody responses to bacterial antigens in aged mice: I. Age-associated changes in antibody responses differ according to the mouse strain

Aging influences the host immune responses in various ways. In aging mice we have studied the antibody responses to two unrelated bacterial antigens. Streptococcus pneumoniae R36a vaccine (Pn) and TNP coupled to Brucella abortus (TNP-BA). Aged animals (20-24 months old) of the C57BL/6 strain had markedly reduced numbers of IgM antibody plaque-forming cells (PFC) to Pn as compared to young/adult mice (2-3 months old). In contrast, the anti-Pn IgM PFC responses of aged BALB/c mice were consistently higher than they were in the young/adult mice. The increased anti-Pn responses were not due to a nonspecific immunostimulation, because the responses of aged BALB/c mice to TNP-BA were lower as compared to the adults. However, the aged BALB/c mice responded relatively poorly to Pn challenge, and their IgG responses (as determined by ELISA plaque assay) demonstrated a very high individual variability. The clonotypic diversity of anti-Pn response in young BALB/c and C57BL/6 is limited, such that the majority of PFC produce antibody that express all idiotopes (Id) of the T15 immunoglobulin encoded in the VH-S107/Vk22 genes. In contrast, the PFC from aged mice are diverse, expressing incomplete T15 Id or none at all, suggesting that the antibodies are encoded by altered T15 genes and by different, non-T15 genes. Our data demonstrate that the age-related changes in the magnitude of antibody response to certain antigens are influenced by the host genetic make-up, and that the changes in magnitude and diversity of antibody response may be unrelated to each other.     

Regulation of T15 idiotype dominance. II. Genes unlinked to the Igh locus regulate T15 dominance of the secondary adoptive transfer response to phosphocholine

We have studied the idiotype and fine specificity of the secondary immune response to phosphocholine (PC) in C57BL (B10, B10.D2, and B.C8) and BALB (BALB/c, BAB-14, and C.B20) congenic strains of mice. In vivo IgM responses of mice from these two genetic backgrounds differed in their T15 idiotypic representation. BALB strains expressed the T15 idiotype on greater than 90% of their IgM, PC-specific plaque-forming cells (PFC), whereas C57BL strains expressed the T15 idiotype on approximately 50% of their IgM PFC. All strains examined expressed greater than 75% PC-inhibitable, VHPC idiotype-positive, IgM PFC. The IgG3 and IgA memory responses were similar to the IgM memory response; BALB strains produced a higher proportion of T15+ PFC than C57BL strains; however, the majority of IgG3 and IgA PFC in all strains were VHPC+, and PC-inhibitable. In contrast, the IgG1 memory response was not dominated by T15+, VHPC+, PC-inhibitable PFC in any of the strains tested. The IgG1 PFC required nitrophenylphosphocholine (NPPC) for efficient inhibition. The IgG2 memory response generally mimicked the IgG1 response with respect to idiotype and specificity. These data demonstrate that the representation of the T15 idiotype in the anti-PC immune response is determined by genes outside both the MHC and Igh genetic loci. Control of T15 expression in secondary IgM, IgG3, and IgA anti-PC responses was examined by using a cell-mixing protocol with primed T and B cells from BALB/c and B10.D2 mice. T15 representation in these responses was determined by the genotype of the B cell, not by the genotype of the helper T cell. Similarly, the B cell genotype was responsible for the idiotypic profile of a primary, in vitro, T-dependent, anti-PC response.     

Repertoire diversity of antibody response to bacterial antigens in aged mice. II. Phosphorylcholine-antibody in young and aged mice differ in both VH/VL gene repertoire and in specificity

Aging of mice is accompanied by both quantitative and qualitative changes in antibody responses to phosphorylcholine (PC), an immunodominant epitope of Streptococcus pneumoniae R36a strain (Pn). In order to study these changes at the molecular level, we generated PC-specific hybridomas from young (3 to 4 mo) and aged (20 to 24 mo) mice of different strains after primary immunization with S. pneumoniae R36a strain. These mAb were tested for Ig VH and VL gene family utilization, idiotopic repertoire, and cross-reactivity with unrelated Ag. Hybridomas from young mice (BALB/c, C57BL/6, and D1.LP) uniformly expressed the VH-S107 and V kappa-22 genes as well as most idiotopes of the T15 family, which were identified with different anti-T15 mAb. In contrast, the PC-reactive mAb from aged mice were quite heterogeneous: only 2 out of 13 utilized VHS107, 1 of 13 used VH7183, and 3 of 13 used VHJ558 gene family. Moreover, none of these mAb used L chain encoded by V kappa 22(0/13), but surprisingly they frequently expressed some of the T15 idiotope. In addition, the PC-binding mAb from aged mice showed broad cross-reactivity with various mouse and foreign proteins, whereas the mAb from young mice did not. These results demonstrate the genetic shift in antibody response of aging mice to PC, which is accompanied by a change in the antibody specificity. Interestingly, the qualitative repertoire change appears to be unrelated to the magnitude of antibody response, for the aged BALB/c mice maintain a very high reactivity to PC.     

In vivo immune response suppression by the supernatant from concanavalin A-activated spleen cells.

Supernatants from concanavalin A- (Con A) activated murine spleen cells have been shown to suppress the in vitro plaque-forming cell (PFC) response to sheep red blood cells (SRBC). The present study examined the effect of such Con A-activated spleen cell supernatants (herein termed CONS) on the in vivo immune response to SRBC in C57BL/6, BALB/c and CDF1 mice. CONS derived from BALB/c spleen cells suppressed direct PFC 4 and 8 days after immunization with 2 X 10(8) SRBC. CONS also suppressed indirect PFC 8 days after immunization, as well as serum hemagglutinins to SRBC. The PFC response of C57BL/6 (H-2b) mice was suppressed as much as that of BALB/c (H-2d) by CONS derived from BALB/c mice, indicating a lack of H-2 specificity of the CONS. In addition to suppression of the antibody response to SRBC, in vivo CONS administration resulted in reduction in spleen cell number. This reduction was not sufficient to explain the decreased PFC response. When the CONS was separated into less than 10,000 m.w. and greater than or equal to 10,000 m.w. fractions, the immunosuppressive activity was found in the less than 10,000 m.w. fraction. This observation suggests that intact interferon, SIRS, and MIF were not responsible for the results obtained.     

Macrophage-mediated suppression of immune responses in Toxoplasma-infected mice. II. Both H-2-linked and -nonlinked control of induction of suppressor macrophages

The suppressive effect of Toxoplasma infection on initiation of memory cells to dinitrophenylated keyhole limpet hemocyanin (DNP-KLH) was drastically different among inbred strains of mice. C57BL/6 (B6), C57BL/10 (B10), and SJL mice showed markedly suppressed secondary anti-DNP responses when infected. In contrast, the suppression did not occur in BALB/c mice. The infected DBA/2 and C3H/He mice produced moderately suppressed responses. In B6 mice, an injection with 1 X 10(2) organisms of T. gondii induced a suppressed elicitation of the memory cells to DNP-KLH. However, in BALB/c mice, the responses were not affected even by inoculation with 1 X 10(4) organisms. The difference in the suppressive effect of infection between B6 and BALB/c mice was also observed in the primary anti-DNP antibody responses to DNP-KLH. Both H-2-linked and -nonlinked genes appeared to be responsible for the regulation of the immunosuppression, since the suppressive effect of infection in B10.D2 mice, which have the B10 background and the same H-2 haplotype as BALB/c, was weaker than that of B10 mice, but stronger than in BALB/c mice. In vitro studies using a primary anti-sheep erythrocytes (SRBC) antibody response system demonstrated that the activation of plastic-adherent suppressor cells by Toxoplasma infection, in which suppressor macrophages have been proved to be the responsible cells for the suppressive activity, was controlled by both H-2-linked and -nonlinked genes.     

Idiotypic analysis of anti-I-Ak monoclonal antibodies. III. T- and B-cell responses to anti-Ia idiotopes are not modulated by syngeneic anti-idiotypic monoclonal antibodies

To investigate whether anti-idiotypic (anti-Id) antibodies activate T cells either directly or indirectly, we examined the ability of syngeneic anti-Id monoclonal antibodies (mAbs) to regulate idiotype (Id) expression, antigen-binding antibody production, and T-cell reactivity to antigen. Our idiotypic system consists of an anti-I-A mAb that carries an infrequently expressed Id. Using three syngeneic anti-Id mAbs (Ab2), we previously defined the idiotype of the 11-5.2.1.9 (11-5) anti-I-Ak mAb. Two of these mAbs, IIID1 and IA2, recognize the same or closely related epitopes on 11-5 and cross react with two additional anti-I-Ak mAbs, 8B and 39J; the third anti-Id mAb, VC6, recognizes a distinct epitope shared by 11-5 and 8B. In the present study, BALB/c (H-2d) mice were primed with varying doses of these anti-Ids and were then boosted with C3H (H-2k) spleen cells. Among 130 such primed mice, the syngeneic anti-Ids when tested at priming doses between 10 ng and 10 micrograms were unable to induce Id production. The priming anti-Id mAbs persisted in the serum of the mice and were detectable as late as 40 days after priming. Ab1 expression was not modulated in BALB/c mice immunized with KLH-coupled Ab2, however, this immunization elicited the production of Ab3 which shared idiotypes with 11-5, 8B, and 39J. BALB/c anti-C3H alloreactive T-cell clones were also not induced by anti-Id priming, nor could they be shown to bind directly to the three Ab2 used. Nevertheless, the proliferative response of one anti-I-Ak specific T-cell clone that recognizes the same epitope as 11-5, 8B, and 39J, was inhibited by the IIID1 and IA2 Ab2. Thus, a T cell can express an idiotype shared by a B cell, but the linked recognition of an Id-associated carrier determinant(s) by an alloreactive T cell is required to elicit an anti-Id antibody response. These results favor the possibility that the activation of T cells is not dependent upon their ability to bind to anti-Id, but rather on their capacity to respond to epitopes of Id-anti-Id antigen-antibody complexes formed on B cells.     

Early development of CD8-negative and CD8-positive MHC-unrestricted cytotoxic cells induced by alloantigen inoculation in mice

Peritoneal cells (PC) in C57B1/6 (B6, H-2b) mice receiving an intraperitoneal (i.p.) injection of allogeneic BALB/c (H-2d) spleen cells demonstrated potent cytotoxic activity against syngeneic, xenogeneic, third-party allogeneic tumors as well as H-2d derived tumors. Maximum cytotoxic activity against various tumors other than H-2d derived tumor, B16 (H-2b) was elicited on day 3 post allosensitization and decreased drastically thereafter, whereas cytotoxic activity against P815 (H-2d) peaked 3 days after the inoculation and maintained the peak activity thereafter. Surface phenotype of PC responsible for the cytotoxic activity against B16 was Thy-1+/-, Lyt-2-, L3T4-, asialo GM1 (AGM1)+, and that of PC against P815 was Thy-1+, Lyt-2+ (or Lyt-2+/-), L3T4-, AGM1+. These phenotypes showed similar phenotypes to the counterparts against B16 and against P815 in spleen cells induced by intravenous inoculation of alloantigen. When mice were pretreated i.p. with anti-AGM1 antibody before the allosensitization, anti-P815 cytotoxic-activity in PC was completely diminished. Similar activity in spleen, however, was enhanced by i.v. treatment with the antibody before the i.v. inoculation of alloantigen. The data clearly demonstrate that in vivo inoculation of B6 mice with normal allogeneic cells induces "NK-like" CD8- cytotoxic cells and "anomalous" CD8+ cytotoxic cells in PC.     

Strain variations in anti-sperm antibody responses and anti-fertility effects in inbred mice

This study provides evidence for polygenic controls of antisperm antibody levels in inbred male mice immunized with syngenic testis and epididymis. H2-linked and non-H2-linked genes were involved. Mice of H-2d haplotype were high responders, whereas those with H-2k haplotype were nonresponders; however, B10.D2/nSnJ mice (H-2d) were also nonresponders. In vitro fertilization inhibition by antisera correlated positively with the serum antisperm antibody levels, particularly with antibody of the immunoglobulin (Ig) G class. Inheritance of antibody response that inhibited in vitro fertilization (IVF) was an autosomal dominant trait, but this was not apparent for the control of antibody levels per se. Since IVF was inhibited by both IgG and fragment antigen-binding (Fab) isolated from immune sera, but not by immune IgG previously absorbed by sperm or testis, the biologic effect is antigen-specific and probably involved blockade of functional antigenic epitopes. Antisera to testis, caput sperm or cauda sperm were found to inhibit IVF to a similar degree. Inbred strains of mice that produced the highest levels of serum antisperm antibodies that inhibited IVF were A/J, SJL/J, DBA/1J and BALB/cByJ mice, and their antisera immunoprecipitated a common sperm antigen molecule of 35,000 to 40,000 Mr. In contrast, C57BL/6 and C57BL/10 mice produced significant antibody levels that had no effect on IVF, and their sera did not react with the 35,000- to 40,000-Mr peak. Moreover, among BALB/c H-2 congenic mice, only antiserum of responder BALB/cByJ (H-2d) mice immunoprecipitated the 35,000- to 40,000 Mr peak. Thus the 35,000- to 40,000-Mr protein may be of functional significance in the fertilization process.     

Idiotype-specific T lymphocytes. I. Regulation of antibody production by idiotype-specific H-2-restricted T lymphocytes

Cytotoxic T lymphocytes (CTL) specific for MOPC-104E myeloma cells of BALB/c origin could be induced in BALB/c, (BALB/c X BALB.B)F1, and (BALB/c X BALB.K)F1 mice. (BALB/c X BALB.B)F1 CTL activity specific for MOPC-104E was effectively inhibited by anti-H-2d but not by anti-H-2b alloantiserum. However, the activity was hardly blocked by specific anti-idiotypic antibodies to MOPC-104E. For further analysis of the recognition of idiotype on target cells by CTL, the effect of those lymphocytes on anti-dextran B1355S antibody-producing B lymphocytes, which have a cross-reactive idiotype to MOPC-104E, was investigated. Lymphocytes from the CTL population did inhibit antibody production by dextran-immune spleen cells, but those from the CTL population specific for irrelevant myeloma cells (MOPC-167) did not. The (BALB/c X BALB.K)F1 CTL population suppressed the antibody production of BALB/c but not of BALB.K. This indicates that F1 cells can preferentially see H-2 antigens of immunizing myeloma cells on target B lymphocytes. The inhibition of antibody production was antigen specific and was only restricted to the PFC that were inhibitable by anti-idiotypic antibodies. The surface phenotypes of the cells that inhibited the antibody production were Thy-1+, Lyt-1-, Lyt-2+, and I-J-. These results strongly suggest that CTL specific for MOPC-104E recognize self H-2 antigens simultaneously with idiotypic determinants on B lymphocytes. Possible immunoregulatory roles of idiotype-specific CTL on antibody production systems are also suggested.     

"Nonspecific" immunoenhancing T cells in tumor-bearing mice include anti-idiotypic subsets

Splenocytes from DBA/2 mice inoculated 3 wk earlier with syngeneic P815 mastocytoma tumor cells produce increased numbers of antibody plaque-forming cells (PFC) when stimulated with either sheep red blood cells (SRBC) or phosphorylcholine (PC) on Streptococcus pneumoniae R36a in vitro. The nature of this nonspecific hyperreactivity was investigated in mixed cultures of purified splenic T and B cells. The addition of T cells from P815 tumor-bearing mice (TP815) into the cultures of normal B cells produced a significant enhancement of the PFC response to both SRBC and PC, when compared with the effect of normal T cells added to control cultures. The idiotypic profile of the enhanced anti-PC response was studied by a PFC-inhibition assay with monoclonal antibodies against two distinct idiotopic determinants (Id) of the T15 family. Normal B cells produced greater than 90% of T15 Id-positive (Id+) PFC. Addition of normal T cells diminished the proportion of T15 Id+ PFC to approximately 60%, whereas the rest of PFC were Id-. Addition of the immunoenhancing TP815 cells into the normal B cells cultures elevated the number of both T15 Id+ and Id- PFC responses, proportionally. However, when TP815 cells were first incubated on T15 protein-coated dishes and the non-adherent fraction was added to B cell cultures, the anti-PC PFC response remained enhanced but consisted of predominently T15 Id- PFC. These observations suggest that the early stage of P815 tumor growth activates various populations of specific helper/amplifier T cells including subsets with anti-idiotypic activity and that the generalized increase of antibody response to various antigens in tumor-bearing mice may be regarded as a polyclonal activation of specific T cells.     

Immune dysfunction associated with graft-vs-host reaction in mice transplanted across minor histocompatibility barriers. II. Reversible defect in T-dependent antibody responses

B cell and Th cell functions were assessed in mice undergoing a graft-vs-host reaction (GvHR) in response to minor histocompatibility Ag by using the plaque-forming cell (PFC) response to the T-independent Ag TNP-Brucella abortus and the T-dependent Ag TNP-SRBC. Bone marrow plus spleen cells from B10.D2 mice were transplanted into lethally irradiated B10.D2 (syngeneic recipient) or H-2d-compatible BALB/c (allogeneic recipient) to produce a chronic form of GvHR. BALB/c recipients of an allogeneic transplant demonstrated a marked and proportional lymphoid depletion of the spleen with normal percentages of B cells, T cells, and CD4+ and CD8+ T cell subsets. Mice with GvHR made normal numbers of PFC/10(5) spleen cells in response to the T-independent Ag, but a significantly depressed number of PFC/10(5) spleen cells to the T-dependent Ag compared with normal B10.D2 mice and with irradiated B10.D2 recipients of syngeneic B10.D2 marrow plus spleen cells. Mice undergoing the minor Ag GvHR made significantly larger numbers of PFC/10(5) spleen cells after secondary immunization with TNP-SRBC compared with controls. In vitro assays demonstrated that B cells from mice with GvHR responded to T help from normal B10.D2 mice and that T cells from mice with GvHR provided help to normal B cells after in vivo immunization. These data demonstrate that radiation chimeras with GvHR in response to minor histocompatibility Ag have relatively normal B cell function and an apparent defect in T helper cell function that is reversible by immunization with appropriate Ag.     

Strain differences in the development of auto-anti-idiotypic antibody regulation with age: genetic linkage to the Igh-C locus

The effect of age on the appearance of anti-idiotype (Id)-blocked, hapten-augmentable plaque-forming cells (PFC) in various strains of mice was investigated. Strains of mice at 2 and 6-11 months of age were immunized with 500 micrograms trinitrophenylated bovine gamma-globulin (TNP-BGG) in complete Freund's adjuvant (CFA) intraperitoneally. Splenic IgM and IgG anti-TNP PFC responses were assayed for anti-Id-blocked, hapten-augmentable PFC 14 days after immunization. It was found that strains differ with regard to the age at which they produce anti-Id-blocked, hapten-augmentable PFC. C57BL/6J (B6), DBA/1J, and C3H/HeJ mice produced a significantly high percentage of hapten-augmentable IgG anti-TNP PFC at 8-9 months of age as compared with the 2-month-old group. In contrast, 129/J, AKR/J, and C57L/J mice produced a significantly low percentage of hapten-augmentable PFC at 6-7 months of age as compared with the 2-month-old group. The CBA/J mice were high-hapten-augmentable plaque producers at both 2 and 7 months of age. SJL/J mice were, on the other hand, low producers at 2 and 11 months of age. Immune sera from high hapten-augmentable plaque-producing strains caused a hapten-reversible block of plaque formation by spleen cells from TNP-BGG-immune C57BL/6J mice and also revealed anti-(anti-TNP F(ab')2-IgG) titer as assayed by passive hemagglutination. This PFC-inhibiting activity in the immune sera of old C57BL/6J mice was an antibody of the IgG2a and IgG3 classes, lacked anti-TNP antibody activity, but reacted with anti-TNP antibody of C57BL/6J origin. Genetic analysis between high hapten-augmentable plaque production and allotypes in the (129/J X B6) crosses of the same H-2b haplotypes revealed that all of the backcrosses and F2 with high hapten-augmentable plaque production had the Igh-1a allele of the high-producer, 129/J mouse. In contrast, the crosses with low hapten-augmentable plaque production were homozygous for the Igh-1b allele of the low-producer, B6 mouse. The data suggest strain differences in the development of auto-anti-idiotypic antibody regulation with age which may be controlled by a gene(s) linked to the Igh-C locus.     

Characterization of the antibody response against the type II collagen induced by anti-idiotypic antibody.

We reported that rabbit anti-idiotypic antibody (Ab2) against mAb, termed 1-5 (Ab1) and reactive with human type II collagen (CII) induced antibody response to CII in DBA/1J mice susceptible to collagen-induced arthritis. In the present study, we further characterized the anti-CII antibody response elicited by Ab2 with respect to epitope specificity, putative genetic background, and IgG subclass. Most of anti-CII antibodies (polyclonal Ab3) derived from Ab2-immunized mice were of the IgG1 subclass. We purified polyclonal Ab3, using a CII-coupled immunoadsorbent column and we developed monoclonal Ab3 from Ab2-immunized mice. Both purified polyclonal Ab3 and two monoclonal Ab3s specifically reacted with a selected epitope on CII, recognized by Ab1. The anti-CII antibody response stimulated by Ab2 was observed in DBA/1J (H-2q, Igh-1c) and DBA/2 (H-2q, Igh-1c) mice, but not in the BALB/c (H-2d, Igh-1a) and C57BL/6 (H-2b, Igh-1b) strains, thereby suggesting that the anti-CII antibody response elicited by Ab2 is controlled by the Igh gene.     

Requirement of I-E molecule for thymocyte apoptosis induced by staphylococcal enterotoxin B in vivo

In vivo administration of bacterial superantigen staphylococcal enterotoxin B (SEB) to BALB/c mice led to thymus atrophy resulting from thymocyte apoptosis. In this study, we demonstrated that SEB induced a substantial reduction in thymocyte numbers in BALB/c, B10. D2 (H-2(d) haplotype), B10.BR, C3H/HeJ, C3H/HeN (H-2(k)), and (BALB/c x B6)F1 (H-2(dxb)), but caused little or no effect in I-E- strains such as B6, B10, A.BY (H-2(b)), and A.SW (H-2(s)) mice. Elimination of CD4(+)CD8(+) cells predominantly accounted for the thymocyte loss, although the numbers of other subpopulations may also be reduced. Thymocyte apoptosis was shown by an increase in the level of DNA fragmentation in BALB/c but not in B6 mice after SEB administration. Treatment with anti-I-Ed monoclonal antibody to BALB/c mice blocked SEB-induced thymocyte apoptosis when anti-I-Ad exerted less effect. In contrast to SEB, staphylococcal enterotoxin A led to comparable levels of thymus atrophy in BALB/c and B6 mice. Studies on the surface marker expression indicated that CD25 expression was upregulated on BALB/c mouse thymocytes but with only a moderate increase in B6 mice. The CD4(+)CD8(+) cells were the major (>90%) population that expressed elevated levels of CD25 in BALB/c mice. An increase in the expression of TCRalphabeta, CD3, and CD69 surface markers was also observed on thymocytes from BALB/c mice, but not from I-E- strains. The differential response of I-E+ and I-E- mice to SEB may be exploited as a model for the study of apoptosis in the thymus.     

Genetic control of immune responses to the 18-kDa protein of Mycobacterium leprae. Different TH1 subsets may be involved in proliferative and delayed-type hypersensitivity responses.

In vitro and in vivo responses to the 18-kDa protein of Mycobacterium leprae have been analysed in different strains of mice. Lymphocytes from BALB/cJ (H-2d), BALB.B (H-2b), B10.BR (H-2k), and B10.M (H-2f) mice primed with 18-kDa protein yielded high T cell proliferative responses, while those from C57BL/10J (H-2b) mice yielded lower responses. Both H-2 and non-H-2 genes contributed to the magnitude of responsiveness. F1 mice from high and low responder strains showed high responsiveness to the 18-kDa protein. Supernatants from lymph node cell cultures prepared from 18-kDa protein-immunised BALB/cJ, B10.BR, and C57BL/10J mice contained IL-2 but no IL-4, indicating that activated T cells from both high and low responder mice were of a TH1 phenotype. Cell cultures from low responder C57BL/10J mice produced less IL-2 than those from high responders. The low responsiveness to the 18-kDa protein in proliferative assays might be due to a low frequency of antigen-specific T cells in the C57BL/10J mouse strain. BALB/cJ, C57BL/10J, and F1 (BALB/cJ x B10.BR) mouse strains were tested for in vivo DTH reactions to the 18-kDa protein. All strains, including C57BL/10J, were high DTH responders. Although DTH effector cells and 18-kDa protein-specific proliferative T cells belong to the TH1 subset, our data comparing high and low responder status indicate that distinct TH1 subpopulations are stimulated in response to the 18-kDa protein of M. leprae.     

Genetic differences in BCG-induced resistance to Schistosoma mansoni are not controlled by genes within the major histocompatibility complex of the mouse.

Induction of nonspecific resistance to Schistosoma mansoni infection after the i.v. injection of viable BCG was investigated in outbred mice and a panel of inbred and H-2 congenic strains. Significant protection was induced in CF1, A/J, C57BL/6, C57BL/10, DBA/2, C57BR, and SJL mice. BALB/c mice were not protected whereas CBA and C3H mice expressed intermediate degrees of protection. Expression of the protective phenomenon is not controlled by genes within the MHC as shown by the marked differences in response between BALB/c and DBA/2 (H-2d) as well as between C57BR and C3H (H-2k) mice. H-2 congenic strains with C57BL/10 background (B10.A and B10.D2) were high responders. BALB.B10 mice carrying the high responder (B10) MHC on the nonresponder (BALB/c) background were not protected. The degree of splenic hypertrophy did not correlate with the expression of nonspecific resistance. These results demonstrate that, in addition to controlling specific immune responses, genetic differences influence the nonspecific protective phenomena related to BCG administration as well.     

Regulation of immune responses via genetically restricted cellular interactions. II. I-region-restricted cooperation between idiotypic and anti-idiotypic B lymphocytes

Immunization of BALB/c mice with MOPC-104E myeloma protein induced idiotype-specific enhancing cells which acted on anti-dextran antibody-producing cells. The enhancing cells have surface phenotypes of B cells. Using BALB/c H-2 congenic strains, it was found that the cooperation between anti-idiotypic-enhancing B lymphocytes and dextran-primed B lymphocytes was controlled by major histocompatibility gene complex. Here we have described the loci which restrict the successful cooperation between B lymphocytes, wherein it was revealed that the interaction was restricted to the I-A and I-E subregions in H-2k haplotype and the I-A subregion in H-2b haplotype. Utilizing several monoclonal antibodies specific for Ia antigens, it was revealed that the enhancing B lymphocyte activity was completely inhibited by the pretreatment of antibody-producing B cells with anti-Ia.7 in H-2d haplotype as well as H-2k, and with anti-I-A antibody in H-2b haplotype. The results suggest that the anti-idiotypic B-lymphocyte response to the self idiotype is under control of H-linked immune response (Ir) gene.