Decreased CD4+CD45RA+ lymphocytes in peripheral blood of systemic lupus erythematosus can recover after separation from patient's sera.

Decrease in CD4+CD45RA+ lymphocytes in peripheral blood of systemic lupus erythematosus (SLE) patients has been reported. In this study, mononuclear cells were separated from peripheral blood of SLE patients, and the CD4+CD45RA+ cells were counted by flow cytometry just after separation and also 1 week after incubation in vitro. Furthermore, healthy lymphocytes were incubated with SLE patient's sera, and the Ca2+ level was measured to investigate the interaction of patient's sera with healthy lymphocytes. The CD4+CD45RA+ lymphocytes were found to be decreased in number on the first day just after separation of lymphocytes, but recovered to normal levels after 1 week culture without patient's sera. The intracellular Ca2+ level in normal lymphocytes increased 1 min after incubation with patient's sera, but not with healthy control sera. These results suggest that CD4+CD45RA+ cells are persistently activated in the peripheral blood of SLE patients, and that their sera contain some extrinsic factors which could activate the lymphocytes.