Decreased macrophage-mediated suppression of lymphocyte activation in chronic renal failure

Interleukin-2 receptor is similarly expressed by activated lymphocytes from patients on chronic hemodialysis and healthy subjects

We studied peripheral blood mononuclear cells (PBMC) from 10 patients on chronic hemodialysis vs 10 healthy controls. T cells were counted by E rosette formation. Interleukin (IL)-2 receptor (IL-2R) carrier cells were identified by Dako-IL-2R, which was chosen as a monoclonal antibody that binds to the alpha chain of IL-2R without interrupting the cell machinery of mitogen-induced IL production. Fluorescein-tagged goat anti-rabbit IgG1* was used for subsequent cell staining, and cells were counted by FACS. Net numbers of PHA-activated IL-2R carrier cells were derived by subtracting appropriate background controls. The average number of these cells relative to numbers of total T cell population in uremic PBMC was statistically not different from healthy controls. Several defects in cellular activation associated with IL-2 mechanisms could be envisaged to account for the impaired proliferative response to PHA, manifested by uremic T cells.

Accessory cell functions in mononuclear cell cultures uremic patients

Mononuclear cells (PBMC) were isolated from dialyzed patients and healthy control subjects. Lymphocyte responses to stimulation with optimal and suboptimal concentrations of lectin (PHA), or stimulation with T cell receptor antibody (Leu 4) were found decreased in the patient cultures. The separate and the combined effects of exogenous interleukin-1 (IL-1) and interleukin-2 (IL-2) were examined in PHA and Leu 4 stimulated cell cultures. Addition of IL-1 did not normalize the decreased proliferation response of the patient cultures. In contrast, addition of IL-2 alone clearly enhanced and almost normalized the response of patient cultures stimulated with suboptimal concentrations of PHA. The combined addition of IL-1 and IL-2 gave no evidence of an additive effect of IL-1 and IL-2. Cell cultures from uremic and normal HLA-identical relative were examined. Substitution of uremic adherent monocytes with normal adherent monocytes as accessory cells did not improve the uremic T cell responses to stimulation with PHA. Furthermore, uremic adherent cells did not suppress the normal T cell responses. These results suggest that uremic accessory cells support T cell activation and, in particular, do not suppress T cell responses. The effect of IL-2 in the present study as well as previous findings of decreased IL-2 production in patients cultures may indicate that uremia primarily influences the proliferation of T cells.

Kinetic analysis of interleukin 2 (IL-2) production and expression of IL-2 receptors by uraemic and normal lymphocytes

The in vitro immune response of lymphocytes from uraemic patients was studied by comparing the in vitro kinetics of interleukin 2 (IL-2) production, the mitogen-induced proliferative response, and the expression of IL-2 receptors by T lymphocytes. The IL-2 production in 26 uraemic cell cultures decreased significantly after 48 h of stimulation with mitogen compared with that of 24 control cultures. The lymphocyte responses to phytohaemagglutinin (PHA), concanavalin A (Con A), and pokeweed mitogen (PWM) increased linearly with time, but the responses of the uraemic cell cultures were significantly lower than those of the control cultures. The relative numbers of cells double-stained for both Tac (IL-2 receptor)/HLA-DR or Tac/Leu 2 were significantly increased in the uraemic cultures as compared with the control cultures at 48 and 72 h. A similar, but not significant, trend was also demonstrated for uraemic cells positive for Tac/Leu 3. These findings were also seen in uraemic lymphocyte cultures supplemented with exogenous IL-2. Thus, the IL-2 production of uraemic lymphocytes seems to be exhausted more rapidly than that of normal lymphocytes, and there is no evidence that the poor proliferative response of uraemic lymphocytes is due to a decreased relative number of cells positive for IL-2 receptors.

Listeriosis in patients with long-term hemodialysis and transfusional iron overload

Over a four-year interval, four cases of Listeria monocytogenes bacteremia were observed among a population of 127 patients undergoing long-term hemodialysis. None had an underlying malignancy or were recently receiving immunosuppressive medications. A search for a predisposing factor suggested a relationship to transfusional iron overload. Although still a rare infection, the possibility of listeriosis must be kept in mind by physicians caring for patients undergoing hemodialysis, particularly those requiring blood transfusions.

Hepatitis B vaccine in patients receiving hemodialysis. Immunogenicity and efficacy

We evaluated the immunogenicity and efficacy of hepatitis B vaccine (Heptavax-B) in a randomized, double-blind, placebo-controlled trial involving 1311 patients receiving hemodialysis in the United States. After three doses of vaccine (40 micrograms each) had been administered, 63 per cent of the patients were antibody-positive. After correction for possible passive transfer of antibodies by blood transfusion, only 50 per cent of vaccine recipients were considered vaccine responders. The incidence of hepatitis B viral infection during the 25 months of the trial was much lower than had been anticipated and was virtually the same in the vaccine and placebo recipients (6.4 and 5.4 per cent, respectively). Four cases of hepatitis B occurred in patients who had an apparent antibody response to the vaccine, but in each case either antibody had reached low or undetectable levels before hepatitis B surface antigen was detected or the patient had been receiving immunosuppressive therapy. This study did not demonstrate the efficacy of the vaccine in a population of patients receiving dialysis in whom both the rate of antibody response to hepatitis B vaccine and the viral attack rate were low. Other measures to control transmission of hepatitis B virus in dialysis units, including surveillance for hepatitis B surface antigen and isolation of patients who are positive for the antigen, must be continued.