IMMUNOLOGICAL EFFECTS OF ANTI-D (WINRHO-SD) IN CHILDREN WITH IMMUNE THROMBOCYTOPENIC PURPURA

Intravenous immunoglobulin (IVIG) is an effective treatment for immune thrombocytopenic purpura (ITP) that induces transient blockade of the reticuloendothelial system (RES) with additional effects including al teration of T lymphocyte subsets and suppression of in vitro T lymphoc yte proliferation. As anti-D also is an effective treatment for ITP, w e investigated its in vitro and in vivo immunologic effects. The in vi tro effects of various agents used in ITP therapy were compared using T lymphocyte proliferation assays. Anti-D caused significantly less in hibition than IVIG or dexamethasone, but non-specific protein was as s uppressive as IVIG. Six children with chronic ITP were studied followi ng anti-D administration. Patients received a single dose of anti-D (W inRho-SD, 50 mu g/kg IV over 5 min) and were studied on day 0, day 7, and 1 month later. Anti-D did not affect T lymphocyte subsets includin g the T cell receptor variable beta repertoire, in vitro T lymphocyte proliferation to mitogens, recall antigens, or interleukin-a, in vitro IgG synthesis induced by pokeweed mitogen, or T lymphocyte cytokine m RNA levels. We conclude that anti-D has no demonstrable in vitro or in vivo effects on lymphocyte enumeration or function, and therefore lik ely is effective in the treatment of ITP primarily through RES blockad e. (C) 1998 Wiley-Liss, Inc.