Pooled human immunoglobulin inhibits IL-4 but not IFN-gamma or TNF-alpha secretion following in vitro stimulation of mononuclear cells with staphylococcal superantigen

Intravenous immunoglobulin preparations have been successfully used in many disorders, where immunomodulation rather than immunoglobulin replacement h as been the goal of therapy. The exact mechanisms by which immunoglobulin e xerts its immunomodulatory effects are unclear, Proposed mechanisms include modification of T cell activation and alteration to cytokine production. A s intravenous immunoglobulin therapy has been used in a number of disorders where superantigens are proposed to play a role in the disease pathogenesi s, we have examined the effect of in vitro human pooled immunoglobulin on c ytokine production from peripheral blood mononuclear cells in response to a ctivation with the Staphylococcal superantigen Staphylococcal enterotoxin B , The authors found inhibition of secretion of interleukin 4 (IL-4) (P<0.00 1) but not interferon gamma (IFN-gamma) (P=0.13) or tumour necrosis factor alpha (TNF-alpha) (P=0.66) by pooled immunoglobulin at concentrations (6 g/ l) which approximate the rise in serum immunoglobulin following in vivo IVI G therapy. Mononuclear cell proliferation was also inhibited by addition of pooled immunoglobulin to superantigen stimulated cultures, These effects d o not relate to specific anti-staphylococcal enterotoxin B antibodies in th e immunoglobulin preparation. The authors show that pooled human immunoglob ulin can differentially modulate the secretion of IL-4 and IFN-gamma in res ponse to superantigen stimulation. (C) 1999 Academic Press.