Expression of NK-lineage markers on peripheral blood lymphocytes with T- helper (Leu3+/T4+) phenotype in B cell chronic lymphocytic leukemia

Heterogeneity within lymphocyte subsets expressing T-helper (T4+/Leu3+) or T-suppressor (T8+/Leu2+) markers was analyzed in 38 patients with B cell chronic lymphocytic leukemia (B-CLL) and in 11 age-matched controls. Co-expression of NK-lineage markers (M1, Leu7) on Leu2+ or Leu3+ cells was investigated by two-color immunofluorescence, and the proportion of granular lymphocytes within each subset was determined by cytochemical staining for acid phosphatase. B-CLL patients and normal controls had similar absolute numbers of cells per microL with T- suppressor phenotype. However, the proportion of Leu2+ cells co- expressing the Leu7 antigen was higher in the B-CLL patients than in the control subjects (54 +/- 3% v 27 +/- 4%, P less than .0001). The absolute number per microL of cells with T-helper phenotype was somewhat decreased in B-CLL patients compared with normal subjects (649 +/- 104 v 799 +/- 33, P less than .02), with a consequent decrease of the helper/suppressor ratio. Furthermore, co-expression of the Leu7 and, more strikingly, of the M1 markers was increased significantly on Leu3+ cells from B-CLL patients compared with normal controls (11 +/- 2% v 2 +/- 0.7%, P less than .002 for Leu7 and 40 +/- 5% v 4 +/- 1%, P less than .00001 for M1). Cytochemical studies showed that a large proportion of Leu3+ cells from B-CLL patients were granular lymphocytes, as suggested by the co-expression of natural killer (NK) cell markers. The emergence of a population of Leu3+ granular lymphocytes with NK markers, which is barely detectable in normal subjects, may provide an explanation for the impairment of T cell functions repeatedly described in B-CLL.     

Identification of high-affinity (Kd 0.35 mumol/L) and low-affinity (Kd 7.9 mumol/L) platelet binding sites for ADP and competition by ADP analogues

Steady-state binding of ADP to blood platelets and isolated membranes has not previously been obtained because of complications arising from metabolism of the ligand and dilution due to its secretion from storage granules. In the present studies, competition binding isotherms (n = 9) using paraformaldehyde-fixed platelets showed that [2-3 H]ADP bound to two sites with a small amount (approximately 5% of total) of nonspecific binding: 410,000 +/- 40,000 sites of low affinity (Kd 7.9 +/- 2.0 mumol/L) and 160,000 +/- 20,000 sites of high affinity (Kd 0.35 +/- 0.04 mumol/L) corresponding to the ADP concentration required for activation in fresh platelets (0.1-0.5 mumol/L). All agonists and antagonists examined were able to compete with ADP at the high-affinity site. The strong platelet agonists 2-methylthio ADP and 2-(3- aminopropylthio)ADP competed with ADP at the high-affinity site with dissociation constant values of 7 mumol/L and 200 mumol/L, respectively. The partial agonist 2',3'-dialdehyde ADP and the weak agonist GDP also competed at the high-affinity site with Kd values of 5 mumol/L and 49 mumol/L, respectively. The sequence of binding affinities of other adenine nucleotides at the high-affinity site corresponded to their relative activities as known antagonists of platelet activation by ADP; namely, ADP(Kd 0.35 mumol/L) approximately equal to ATP (Kd 0.45 mumol/L) much greater than AMP (Kd 360 mumol/L). Adenosine and 2-chloroadenosine did not compete with ADP. ADP binding to the high-affinity site was inhibited by p-mercuribenzene sulfonate (Ki 250 mumol/L) but only very weakly by 5'-p- fluorosulfonylbenzoyladenosine (Ki 1 mmol/L). All the above nucleotides also competed with ADP at the low-affinity sites but, because of the high concentrations of competing nucleotide required, dissociation constants at this site were obtained only for ATP (21 mumol/L), 2-MeS ADP (200 mumol/L) and 2',3'-dialdehyde ADP (270 mumol/L). 8-Bromo ADP competed strongly with ADP at the high-affinity site (Kd 0.40 mumol/L) but weakly if at all at the low-affinity site. 8-Bromo ADP inhibited platelet activation induced by ADP (EC50 approximately 100 mumol/L) but not by collagen, thrombin, or ionophore A23187.(ABSTRACT TRUNCATED AT 400 WORDS)     

The impact of late acute rejection after cadaveric kidney transplantation

BACKGROUND: Acute graft rejection (AR) following renal transplantation results in reduced graft survival. However, there is uncertainty regarding the definition, aetiology and long-term graft and patient outcome of AR occurring late in the post-transplant period. AIM: To determine if rejection episodes can be classified by time from transplantation by their impact on graft survival into early acute rejection (EAR) and late acute rejection (LAR). MATERIALS AND METHODS: 687 consecutive adult renal transplant recipients who received their first cadaveric renal transplant at a single centre. All received cyclosporine (CyA)-based immunosuppression, from 1984 to 1996, with a median follow-up of 6.9 yr. Details were abstracted from clinical records, with emphasis on age, sex, co-morbid conditions, HLA matching, rejection episodes, patient and graft survival. ANALYSIS: Patients were classified by the presence and time to AR from the date of transplantation. Using those patients who had no AR (NAR) as a baseline, we determined the relative risk of graft failure by time to rejection. The characteristics of patients who had no rejection, EAR and LAR were compared. RESULTS: Compared with NAR, the risk of graft failure was higher for those patients who suffered a rejection episode. A much higher risk of graft failure was seen when the first rejection episode occurred after 90 d. Thus, a period of 90 d was taken to separate EAR and LAR (relative risk of 3.06 and 5.27 compared with NAR as baseline, p<0.001). Seventy-eight patients (11.4%) had LAR, 271 (39.4%) had EAR and 338 (49.2%) had NAR. The mean age for each of these groups differed (LAR 39.6 yr, EAR 40.8 yr compared with NAR 44 yr, p<0.003). The 5-yr graft survival for those who had LAR was 45% and 10-yr survival was 28%. HLA mismatches were more frequent in those with EAR vs. NAR (zero mismatches in HLA-A: 36 vs. 24%, HLA-B: 35 vs. 23% and HLA-DR: 63 vs. 41%, p<0.003). There was no difference in mismatching frequency between NAR and LAR. CONCLUSIONS: AR had a deleterious impact on graft survival, particularly if occurring after 90 d. AR episodes should therefore be divided into early and late phases. In view of the very poor graft survival associated with LAR, it is important to gain further insight into the main aetiological factors. Those such as suboptimal CyA blood levels and non-compliance with medication should be further investigated with the aim of developing more effective immunosuppressive regimens in order to reduce the incidence of LAR.     

A prospective study of oral lesions and their predictive value for progression of HIV disease

OBJECTIVE: This report evaluates and compares individual oral lesions and combinations of lesions in predicting progression-free survival in a seroprevalent cohort of men and women with HIV infection. DESIGN: This was a prospective study of HIV-infected patients, initially AIDS-free, followed for approximately 30 months. SETTING: Patients were volunteers examined at an academic medical center and at an inner-city hospital in New York. Participants identified themselves as homosexual men or as injection drug users (IDU).OUTCOME MEASURES: The primary outcome being assessed is time from a baseline oral examination until the development of an AIDS-defining condition or death from any cause within 12 months of the last study visit. Correlation is measured by relative risk (RR).RESULTS: While oral lesions were not predictive of progression among subjects with CD4s=200, they were highly predictive of progression among those with CD4<200.For subjects with CD4<200, the only individual lesion that was significantly associated with progression-free survival was oral candidiasis (RR=4.12, P= 0.009).Positivity for one or more lesions in a set demonstrated greater prognostic value among those with CD4<200, with RR's of 6.03 (P= 0.018) for the set consisting of oral candidiasis, hairy leukoplakia, and necrotizing ulcerative gingivitis (NUG), and 8.77 (P= 0.036) for the set consisting of the above lesions plus linear gingival erythema (LGE).Analysis by cohort suggested that the improvement in correlation was stronger in homosexual men than in IDU, but this question could not be resolved conclusively with these data. CONCLUSIONS: Lesion sets might be better prognosti-cators of progression-free survival than individual lesions among HIV-infected subjects with CD4<200.Prognostic value of the core lesion set (oral candidiasis and hairy leukoplakia) was enhanced by the addition of other lesions (NUG and LGE) not usually included in HIV staging systems. These results suggest that staging systems for HIV might be improved by the inclusion of other, survival-related oral lesions.     

The formation and function of the neutrophil phagosome

Neutrophils are the most abundant circulating leukocyte and are crucial to the initial innate immune response to infection. One of their key pathogen-eliminating mechanisms is phagocytosis, the process of particle engulfment into a vacuole-like structure called the phagosome. The antimicrobial activity of the phagocytic process results from a collaboration of multiple systems and mechanisms within this organelle, where a complex interplay of ion fluxes, pH, reactive oxygen species, and antimicrobial proteins creates a dynamic antimicrobial environment. This complexity, combined with the difficulties of studying neutrophils ex vivo, has led to gaps in our knowledge of how the neutrophil phagosome optimizes pathogen killing. In particular, controversy has arisen regarding the relative contribution and integration of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-derived antimicrobial agents and granule-delivered antimicrobial proteins. Clinical syndromes arising from dysfunction in these systems in humans allow useful insight into these mechanisms, but their redundancy and synergy add to the complexity. In this article, we review the current knowledge regarding the formation and function of the neutrophil phagosome, examine new insights into the phagosomal environment that have been permitted by technological advances in recent years, and discuss aspects of the phagocytic process that are still under debate.