In view of the fact that IL-10 propagated the in vitro differentiation of B cells into plasma cells and, as CD4 T cells are important B cell helpers and show pronounced up-regulation of IL-10 with progressing disease (Figure 4a), we examined whether IL-10 expression in CD4 T cells from donors with manifest lupus coincides with further B cell-helper molecules. The gene discussed is CD4; the disease is systemic lupus erythematosus.