Investigation of B cell function and B cell stimulatory factors in patients with systemic lupus erythematosus

Abstract

The immunological abnormality of systemic lupus erythematosus (SLE) is characterized by polyclonal B cell activation. Whether polyclonal B cell activation is caused by B cell abnormality or effect of B cell stimulatory factors (BSF) were investigated in this study. B cell function of SLE patients and normal individuals were measured by three methods, 1) Staphylococcus aureus Cowan I (SAC) response, 2) BCGF response and 3) BCGF response after SAC stimulation. There was no significant difference in B cell function among three groups (active SLE group, inactive SLE group and normal individuals group). Supernatants of PHA stimulated T cell and SAC stimulated B cell contained BCGF and BCDF activities. T cell derived BCGF and BCDF activities in active SLE patients revealed higher than in inactive SLE patients and normal individuals. There was no significant difference among these group in B cell derived BCGF like activity, but BCDF like activity revealed higher in active SLE patients than in inactive SLE patients and normal individuals. High level of BCGF and BCDF like activities were shown also in sera of active SLE patients found than in those of other two groups. As mentioned above, these results suggested that polyclonal B cell activation in SLE patients might be chiefly caused by increased T cell derived BCGF and BCDF activities, and B cell derived BSF respond to B cell as supportive factors.