B cell hyperactivity and its relation to distinct clinical features and the degree of disease activity in patients with systemic lupus erythematosus.

Peripheral blood B cells that were actively proliferating, those actively secreting immunoglobulin, and those expressing an early activation marker, Ba antigens, on the surfaces were quantitated in 25 patients with systemic lupus erythematosus (SLE). B cell hyperactivity was found in almost all of the SLE patients, as demonstrated by any one of these measures of B cell activity. Moreover, we observed a strong positive correlation between the degree of disease activity and the amount of spontaneous incorporation of 3H-thymidine by B cells; the magnitude of the increase in frequency of spontaneous Ig-secreting cells in peripheral blood correlated strikingly with certain clinical features in these patients. Our findings suggest that there is heterogeneity of B cell hyperactivity in individual patients with SLE and, thus, that clinical subsets of SLE can be identified on the basis of B cell hyperactivity.