Two types of antibodies inhibiting interleukin-2 production by normal lymphocytes in patients with systemic lupus erythematosus.

Decreased interleukin-2 (IL-2) production by lymphocytes in vitro has previously been demonstrated in patients with systemic lupus erythematosus (SLE). In the present study, we examined whether inhibitory factors in SLE patient sera are involved in defective IL-2 production. Our results indicate that purified IgG fractions of some SLE sera inhibit IL-2 production at 2 distinct phases of the IL-1-dependent IL-2 production system in vitro: first, by binding to adherent cells and probably inhibiting IL-1 production by macrophages, similar to the action of anti-HLA-DR antibodies, and second, by binding to T cells and blocking the interaction of IL-1 and T cells.