[Immune complexes induce the secretion of Th2 cytokines in human monocytes]

Two experimental models of immune complexes were used to study the secretion of interleukin (IL)-10, IL-6, IL-1 beta and TNF-alpha by human monocytes in vitro. Immune complexes formed of tetanus toxoid and polyclonal anti-tetanus toxoid antiserum as well as heat-aggregated human serum immunoglobulins induced the release of IL-6 and IL-10 in a dose- and antigen: antibody ratio-dependent manner. Antigen-antibody complexes formed near equivalence were most effective in induction of a cytokine response. Additionally, we demonstrated that endogenously synthesized IL-10 limited the immune complex-induced secretion of proinflammatory cytokines tumor necrosis factor-alpha, IL-6 and IL-1 beta. IL-10 is an anti-inflammatory cytokine and closely associated with the T helper type 2 (Th2) immune response. We conclude that immune complexes, besides their well known ability to cause acute and chronic inflammation, can mediate immunosuppressive effects and influence the balance of Th1/ Th2 responses.