Impaired T cell proliferation and zeta chain phosphorylation after stimulation with staphylococcal enterotoxin-B in hemodialysis patients.

BACKGROUND

Patients on regular hemodialysis treatment are in an immunodeficiency state. Several studies have shown defective T cell proliferation after stimulation with various agents. Staphylococcal enterotoxin B (SEB) is a MHC-dependent superantigen that triggers proliferation of a large proportion of T cells. T cell activation after stimulation with SEB parallels normal T cell signal transduction. An important and early event in this transduction pathway is the phosphorylation of the zeta chain. In this study, T cell proliferation and zeta chain phosphorylation after stimulation with SEB were evaluated.

METHODS

Peripheral blood mononuclear cells (PBMCs) from 24 patients and 14 healthy individuals were isolated and cultured with or without stimulation with SEB (1 ng/ml). Cell proliferation was estimated by immunoenzymatic measurement of bromodeoxyuridine uptake. PBMCs from 8 patients and 6 healthy individuals were isolated and pulsed for 2 min with or without SEB (10 microg/ml). Zeta chain phosphorylation was estimated by immunoprecipitation and immunoblotting with antiphosphotyrosine antibody.

RESULTS

Lymphocyte proliferation index after SEB stimulation was lower in hemodialyzed patients. Stimulation of T cells with SEB also resulted in a lower zeta chain phosphorylation in hemodialyzed patients.

CONCLUSIONS

Lymphocyte proliferation after MHC-dependent stimulation is impaired in hemodialyzed patients. This proliferation defect is due to impaired zeta chain phosphorylation.