To define the abnormalities in homeostasis of B-1 B lymphocytes compartments in human SLE.

Perpheral blood was obtained from 7 patients with untreated active SLE patients and same patients at the time of incative disease after immunosuppressive therapy. The frequencies of CD5⁺CD45RA^int B-1a B lymphocyte, and CD5⁺CD45RA^low B-1b B lymphocyte, CD5^-CD45RA^high conventional B-2 lymphocyte subsets were analyzed. For the control group, peripheral blood from 7 healthy adults and 7 patients with infectious fever were utilized.

B-1a B lymphocyte subset was found at high frequency in active SLE patients compared to the fever control(33.5±15.0% vs 20.1±5.3%,p=0.01). In contrast, B-2 B lymphocyte subset was found at lower frequency compared to the fever control (65.6±15.1% vs 77.9±5.6%,p=0.04). No difference in frequency of B-1b B lymphocyte subsets was found between active SLE and the control. After immunosuppressive theray, B-1b B lymphocyte subset was markedly decreased with increase in B-2 B lymphocyte subset(p=0.05).

These results indicate that there are abnormalities in B cell conpartments with expansion of B-1a B lymphocyte subset and contraction of B-2 B lymphocyte subset associated with the disease activity in patients wite SLE.