Lack of effect of Candida albicans mannan on development of protective immune responses in experimental murine candidiasis

Candida albicans mannoprotein (MAN) administered to mice before or during immunization with viable C. albicans downregulates MAN-specific delayed hypersensitivity. In the experiments reported here we determined the effect of MAN downregulation on protective immunity in minimally immunized mice, i.e., mice exposed to C. albicans either intradermally or intragastrically, and in maximally immunized mice, i.e., mice immunized by a combination of intradermal and intragastric exposure, in experimental systemic candidiasis. MAN suppression did not induce statistically significant alterations in the protective responses in experimental candidiasis, although 8 of 12 groups of mice treated with MAN had fewer CFU of C. albicans in their kidneys than their non-MAN-treated counterparts. The results emphasize the lack of correlation of delayed hypersensitivity with protection in candidiasis and suggest that MAN may contain epitopes involved in the protective response.     

Protective immune responses against protease-like antigens of the murine malaria parasite Plasmodium vinckei

The Plasmodium falciparum proteins serine repeat antigen (SERA) and serine repeat protein homologue (SERPH) have similarity in sequence with cysteine proteases in a well-conserved protease domain. We identified three SERA homologues from the murine malaria parasite Plasmodium vinckei and evaluated immune responses to the protease domains of these proteins. Mice that developed protective immunity to P. vinckei after serial infection and cure demonstrated humoral and cell-mediated responses against the SERA homologue protease domains. Mice immunized with Salmonella typhimurium expressing the protease domain of one of these antigens demonstrated cellular responses against the antigen and increased survival against lethal challenge with P. vinckei. Our results suggest that the protease domains of SERA and SERPH are worthy of additional study as potential components of a malaria vaccine.     

The induction of immune responses to murine malignant mesothelioma by IL-2 gene transfer

OBJECTIVE: The incidence of congenital hypothyroidism (CH) has been shown to vary among different parts of the world. This could result from environmental or hereditary factors. Studies of other congenital diseases have shown that immigrants tend to retain the incidence of their country of origin while their children acquire the incidence of their new homeland, suggesting an environmental influence. This study aimed to assess the differences in the incidence of CH among immigrants from different parts of the world and to study the effects of immigration on its occurrence. METHODS: During the 9-year period between 1979 and 1987, 196 Jewish infants with primary CH were born in Israel; this constitutes an incidence of 1:3354 live births. We collected data from hospitals, endocrine pediatric clinics and the children's parents regarding the birth place of the parents and grandparents of those infants. These data were compared with the birth place of the parents and grandparents of all infants born in Israel during that period in order to learn about the incidence of CH among infants of different origins and to compare the incidence between children of parents born in Israel and those of immigrants of the same grandparental origin. RESULTS: CH incidence was lower among offspring of mothers and fathers of Israeli origin (1:4717 and 1:4255 live births respectively) and higher among those of African mothers (1:2950) and Asian fathers (1:2941). Parents of Asian or African origin, born in Israel have a lower incidence of CH-affected children compared with parents of the same origin born in their own continent. This trend is reversed for European and American parents, for whom being born in Israel is related to an increase in the CH incidence in their children. The difference in CH incidence between offspring of parents born in Israel and those of parents born in their original country was statistically significant (P < 0.05). In the different origin groups the gender of the parent did not influence significantly the incidence of CH. CONCLUSIONS: Environmental changes resulting from immigration can influence the incidence of congenital hypothyroidism.     

Heat-killed Listeria monocytogenes as an adjuvant converts established murine Th2-dominated immune responses into Th1-dominated responses

We investigated the capacity of heat-killed Listeria monocytogenes (HKL), a potent stimulator of the innate immune system, as a vaccine adjuvant to modify both primary and secondary Ag-specific immune responses. Mice immunized with the Ag keyhole limpet hemocyanin (KLH) mixed with HKL generated a KLH-specific primary response characterized by production of Th1 cytokines and large quantities of KLH-specific IgG2a Ab. Moreover, administration of KLH with HKL as an adjuvant reversed established immune responses dominated by the production of Th2 cytokines and high levels of KLH-specific IgE and induced a Th1-type response with high levels of IFN-gamma and IgG2a and low levels of IgE and IL-4. Neutralization of IL-12 activity at the time of HKL administration blocked the enhancement of IFN-gamma and reduction of IL-4 production, indicating that IL-12, induced by HKL, was responsible for the adjuvant effects on cytokine production. These results suggest that HKL as an adjuvant during immunization can successfully bias the development of Ag-specific cytokine synthesis toward Th1 cytokine production even in the setting of an ongoing Th2-dominated response. Thus, HKL may be clinically effective in vaccine therapies for diseases such as allergy and asthma, which require the conversion of Th2-dominated immune responses into Th1-dominated responses.     

Isotype-specific antibody responses to foot-and-mouth disease virus in sera and secretions of "carrier' and "non-carrier' cattle

Isotype-specific antibody responses to foot-and-mouth disease virus (FMDV) were measured in the sera and upper respiratory tract secretions of vaccinated and susceptible cattle challenged with FMDV by direct contact or by intranasal inoculation. A comparison was made between cattle that eliminated FMDV and those that developed and maintained a persistent infection. Serological and mucosal antibody responses were detected in all animals after challenge. IgA and IgM were detected before the development of IgG1 and IgG2 responses. IgM was not detected in vaccinated cattle. Challenge with FMDV elicited a prolonged biphasic secretory antibody response in FMDV "carrier' animals only. The response was detected as FMDV-specific IgA in both mucosal secretions and serum samples, which gained statistical significance (P < 0.05) by 5 weeks after challenge. This observation could represent the basis of a test to differentiate vaccinated and/or recovered convalescent cattle from FMDV "carriers'.     

Antiviral immune responses in Itk-deficient mice

Mice lacking Itk, a T-cell-specific protein tyrosine kinase, have reduced numbers of T cells and reduced responses to allogeneic major histocompatibility molecules. This study analyzed antiviral immune responses in mice deficient for Itk. Primary cytotoxic T-lymphocyte (CTL) responses were analyzed after infection with lymphocytic choriomeningitis virus (LCMV), vaccinia virus (VV), and vesicular stomatitis virus (VSV). Ex vivo CTL activity was consistently reduced by a factor of two to six for the different viruses. CTL responses after restimulation in vitro were similarly reduced unless exogenous cytokines were added. In the presence of interleukin-2 or concanavalin A supernatant, Itk-deficient and control mice responded similarly. Interestingly, while LCMV was completely eliminated by day 8 in both Itk-deficient and control mice, VV cleared from itk-/- mice with delayed kinetics. Antibody responses were evaluated after VSV infection. Both the T-cell-independent neutralizing immunoglobulin M (IgM) and the T-cell-dependent IgG responses were similar in Itk-deficient and control mice. Taken together, the results show that CTL responses are reduced in the absence of Itk whereas antiviral B-cell responses are not affected.     

Host immune potentiation of drug responses to a murine mammary adenocarcinoma. II. Effect of melphalan therapy on the host immune system

The role of chemotherapy in influencing tumor-specific immunity to a mouse mammary adenocarcinoma was investigated. By studying different stages of tumor growth we were able to identify several factors important to drug-induced tumor regression: (1) antibody response, (2) delayed hypersensitivity, (3) sensitivity of tumor cells to immune attack and (4) tumor burden. The presence of tumor-specific delayed hypersensitivity and circulating antibody as well as specifically armed monocytes in the tumor mass characterize the T1699 adenocarcinoma. Successful chemotherapy had previously been shown to depend on prior establishment of the above immune responses. Treatment with alkylating agents was marked in all animals by abrogation of a humoral response to the tumor when drug was given early (day 7), and was associated with poor chemotherapeutic results. Later treatment (day 10) was associated with depression of antibody titers only in the minority of animals not responding to drug and prolongation of the delayed hypersensitivity response in all treated animals. Tumors recurring following initial drug-induced regression were marked by lack of delayed hypersensitivity in the host, lack of drug response and suppression of humoral immunity following treatment. Successive passage of cells from these resistant tumors led to decreasing sensitivity to chemotherapy despite established immunity on the part of the host. The selection of tumor cells resistant to immune destruction rather than drug resistance per se appeared to pay a role. Melphalan was thus able to affect both favorably and adversely the immune factors important to drug-induced regression.     

Cell-mediated immune responses in patients with paracoccidioidomycosis

The morphology of lymph node tissue from normal hamsters and from hamsters experimentally infected with Treponema pertenue Gauthier was compared by means of light and electron microscopy. The capsules of the lymph nodes from infected hamsters showed an increased thickness in comparison with those of the non-infected animals. The infected lymph nodes differed from normal lymph nodes by small accumulations of neutrophilic leucocytes in the cortical areas. In addition, the amount of intercellular collagenous matrix present between large elongated cells was greatly increased in lymph nodes from infected animals. Electron microscopy of thin sections of infected lymph nodes showed intercellularly located treponemes in the leucocyte infiltration areas. These regions also showed the increased amounts of the collagenous matrix. Treponemes were occasionally found intracellularly in macrophages. These treponemes did not show their typically helical shape, but were present as spherical forms or cysts.     

Gastrointestinal immune responses in HIV infected subjects

Biliary atresia (BA) is characterized by luminal obstruction of the extrahepatic bile duct with fibrous remnants. The authors reviewed ultrasonographic examinations of the fibrous tissue in the bifurcation of the portal vein at the porta hepatis and identified the triangular- or tubular-shaped echogenic density, the so-called "triangular cord" (TC), in the vicinity of the portal vein on a transverse or longitudinal scan. In this prospective study, the authors investigated whether TC was useful in the noninvasive diagnosis of biliary atresia in 18 infants who had persistent neonatal jaundice. This was done by comparing the ultrasonographic examination with the histopathologic examination (HPE) of liver specimens obtained from a needle biopsy. The TC was identified in nine patients, all of whom were confirmed to have BA by HPE. The TC was not observed in the other nine patients, who had neonatal hepatitis (NH). The mean size of the TC was 13 mm (wide) x 6 mm (thick) (width range, 5 to 21 mm; thickness range, 4 to 12 mm). The diagnosis of BA was confirmed at the time of Kasai hepatoportojejunostomy in eight of the nine patients whose TC was noted by ultrasonography (US). The other patient was discharged because his parents refused the operation; he died of liver failure at 15 months of age. The nine patients with absent TC were treated medically for NH. Eight of them improved clinically. The other, diagnosed to have NH by needle and wedge liver biopsies, was reexamined 40 days after the initial examination because of worsening jaundice. A 18 x 12-mm TC was visualized ultrasonographically. Additionally, a percutaneous liver biopsy specimen showed BA with severe portal fibrosis and ductal proliferation. The patient underwent a Kasai hepatoportoenterostomy. On the basis of these results, the authors conclude that TC is a very specific ultrasonographic finding, representing the fibrous cone at the porta hepatis, and is a useful tool in the noninvasive diagnosis of BA. However, early exploration or close US follow-up is recommended for any patient suspected of having BA clinically, even if a liver biopsy confirms the NH.     

MHC regulation of immune responses

The major histocompatibility complex is a group of complex genes situated on the short arm of chromosome 6 in humans. They play an important role in the regulation of the immune response. Autoimmune blistering disease provides an ideal model for studying the role of MHC in autoimmunity. The diseases are organ specific, and in some of them the relevant antigen has been cloned and sequenced. Such information on the antigen will help further define the interactions of the Ag, MHC, and TCR. Use of family studies hopefully will define and localize susceptibility alleles, so that any genetic susceptibility can be identified at the molecular level. It is from these molecular perspectives that molecular therapies could be assigned to restore the immune system.     

Oral keratinocyte immune responses in HIV-associated candidiasis

Technetium-99m is the most commonly used radionuclide in routine nuclear medicine imaging procedures. Development of 99mTc-labeled receptor-specific imaging agents for studying the central nervous system is potentially useful for evaluation of brain function in normal and disease states. A novel 99mTc-labeled tropane derivative, [99mTc]TRODAT-1, which is useful as a potential CNS dopamine transporter imaging agent, was evaluated and characterized. After i. v. injection into rats, [99mTc]TRODAT-1 displayed specific brain uptake in the rat striatal region (striatum-cerebellum/cerebellum ratio 1.8 at 60 min), where dopamine neurons are concentrated. The specific striatal uptake could be blocked by pretreating rats with a dose of competing dopamine transporter ligand, beta-CIT (or RTI-55, i.v., 1 mg/kg). However, the specific striatal uptake of [99mTc]TRODAT-1 was not affected by co-injection of excess free ligand (TRODAT-1, up to 200 microg per rat) or by pretreating the rats with haloperidol (i.v., 1 mg/kg). The specific uptake in striatal regions of rats that had prior 6-hydroxydopamine lesion in the substantia nigra area showed a dramatic reduction. The radioactive material recovered from the rat striatal homogenates at 60 min after i.v. injection of [99mTc]TRODAT-1 showed primarily the original compound (>95%), a good indication of in vivo stability in brain tissue. Similar and comparable organ distribution patterns and brain regional uptakes of [99mTc]TRODAT-1 were obtained for male and female rats. Ex vivo autoradiography results of rat brain sections further confirmed the high uptake and retention of [99mTc]TRODAT-1 in the striatal region. In vitro binding studies measuring the affinity to dopamine transporters for the free ligand, TRODAT-1, and a nonradioactive rhenium derivative, Re-TRODAT-1, showed Ki values of 9.7 nM and 14.1 nM, respectively. Behavioral studies in rats using the free ligand, TRODAT-1 and Re-TRODAT-1 indicated that, unlike other tropane derivatives, they displayed no effect on locomotor activity, suggesting low toxicity. These results strongly support the conclusions that this novel 99mTc radioligand binds selectively to dopamine transporters in the brain and that is is potentially useful for in vivo assessment of the loss of dopamine neurons in Parkinson's and other neurodegenerative diseases.     

Humoral and cellular immune responses in the murine respiratory tract following oral immunization with cholera toxin or Escherichia coli heat-labile enterotoxin

Cholera toxin (CT) and Escherichia coli heat-labile enterotoxin (LT) are the strongest mucosal immunogens identified to date and are also good adjuvants when given orally together in combination with unrelated antigens. We used these potent immunogens to monitor local and systemic immune responses following oral immunization of BALB/c mice, and compared their action on the following: (a) immunoglobulin production rates (IgG, IgM and IgA) in mucosal inductive (Peyer's patches-PPs), effector (intestinal lamina propria-LP, respiratory tract) and systemic (spleen) sites; (b) analysis of systemic antigen-specific antibodies (IgG subclasses, IgA and IgE); (c) time monitoring of fecal anti-CT and anti-LT antibodies, and (d) in vivo relevance of interleukin-6 (IL-6) to mucosal responses. Both mucosal immunogens elicited specific antibody responses (IgA, IgG) not only in the gastrointestinal tract (PP's and intestinal LP), but also in the respiratory tract and spleens of orally immunized mice. These mucosal responses were accompained by elevated secretion of IL-6 in all investigated tissues, indicating involvement of this cytokine in B-cell maturation processes. Furthermore, oral immunization with CT and LT induced elevated serum titers of IgG1 followed by IgG2a, IgG2b, IgG3 and IgA, while high antigen-specific IgA and IgG1 responses were found in fecal extracts. These findings illustrate the action of orally administered CT and LT, respectively, on several humoral and cellular immune responses not only at the gastrointestinal tract, the application site, but also in distant mucosal effector sites such as the respiratory tract. These data suggest the potential use of these mucosal adjuvants in oral immunization strategies to improve the local immune response in remote mucosal tissues, in accordance with the concept of a common mucosa-associated immune system.     

Genetic immunization generates cellular and humoral immune responses against the nonstructural proteins of the hepatitis C virus in a murine model

Exposure to hepatitis C virus (HCV) is associated with a high prevalence of persistent viral infection and the development of chronic liver disease and hepatocellular carcinoma. Recovery from acute infection may depend upon the generation of broad-based cellular immune responses to viral structural and nonstructural proteins. We used the DNA-based immunization approach in BALB/c mice to determine whether the HCV nonstructural proteins NS3, NS4, and NS5 will induce Ab responses, CD4+ Th cell proliferation, and cytokine release in response to stimulation by recombinant proteins as well as generate CD8+ CTL activity both in vitro and in vivo. We found that the nonstructural proteins were particularly good immunogens and produced cellular immune responses when administered as a DNA construct. Indeed, a tumor model was established following inoculation of syngenic SP2/0 cells stably transfected with NS5. We observed protection against tumor formation and growth only in mice immunized with the NS5-encoding DNA construct, establishing the generation of significant CTL activity in vivo by this technique. The results indicate that genetic immunization may define the cellular immune response of the host to HCV nonstructural proteins and is a promising approach for vaccine development.     

Antiviral immune responses in CTLA4 transgenic mice

The role of B7 binding CD28 in the regulation of T- and B-cell responses against viral antigens was assessed in transgenic mice expressing soluble CTLA4-Hgamma1 (CTLA4-Ig tg mice) that blocks B7-CD28 interactions. The results indicate that transgenic soluble CTLA4 does not significantly alter cytotoxic T-cell responses against replicating lymphocytic choriomeningitis virus (LCMV) or vaccinia virus but drastically impairs the induction of cytotoxic T-cell responses against abortively replicating vesicular stomatitis virus (VSV). While the T-independent neutralizing immunoglobulin M (IgM) responses were within normal ranges, the switch to IgG was reduced 4- to 16-fold after immunization with abortively replicating VSV and more than 30-fold after immunization with an inert VSV glycoprotein antigen in transgenic mice. IgG antibody responses to LCMV, as detected by enzyme-linked immunosorbent assay and by neutralizing action, were reduced about 3- to 20-fold and more than 50-fold, respectively. These results suggest that responses in CTLA4-Ig tg mice are mounted according to their independence of T help. While immune responses to nonreplicating or poorly replicating antigens are in general most dependent on T help and B7-CD28 interactions, they are most impaired in CTLA4-Ig tg mice. The results of the present experiments also indicate that highly replicating viruses, because of greater quantities of available antigens and by inducing as-yet-undefined factors and/or cell surface changes, are capable of compensating for the decrease in T help caused by the blocking effects of soluble CTLA4.     

Spaceflight and development of immune responses

The NIH.R1 Space Shuttle experiment was designed to study the effects of spaceflight on rodent development. Pregnant rats were flown on the Space Shuttle for 11 days, and pregnant control rats were maintained in animal enclosure modules in a ground-based chamber under conditions approximating those in flight. Additional controls were in standard housing. The effects of the flight on immunological parameters of dams, fetuses, and pups were determined. Blastogenesis of spleen cells in response to mitogen was inhibited in flown dams but was not inhibited in cells from their pups. Interferon-gamma production by spleen cells showed a trend toward inhibition in flown dams but not in their pups. The response of bone marrow cells to colony-stimulating factor showed a trend toward inhibition after spaceflight in dams, but the response of fetus and pup liver cells was not inhibited. Total serum IgG was not affected by spaceflight. None of the examined immune parameters that were altered in rat dams after spaceflight was found to be altered in their offspring.     

Efficient immune responses in mice lacking N-region diversity

Mice with a null mutation in the terminal deoxynucleotidyl transferase (TdT) gene harbor immunoglobulin and T cell receptor repertoires essentially devoid of N-region diversity. Consequently, the CDR3 loops important for antigen recognition are shorter and considerably less diverse than those of wild-type controls. We find surprisingly normal immune responses in TdT0 mice, as regards both efficiency and specificity. This provokes a reconsideration of the assumption that N-region diversity is required for an effective T and B cell repertoire.