Effect of intravenous immune globulin on natural killer cell activity: possible association with autoimmune neutropenia and idiopathic thrombocytopenia.

Natural killer cell (NK) activity was assessed in patients before and after treatment with intravenously administered immune globulin (IVIG). In eight patients with hypogammaglobulinemia or agammaglobulinemia receiving 300 mg/kg/dose IVIG every 4 weeks, NK activity was significantly lower after therapy than before. In two patients, one with idiopathic thrombocytopenic purpura and one with autoimmune neutropenia, receiving high doses (2 gm/kg) of IVIG, NK activity was unusually high before therapy. After treatment, NK activity decreased in correlation with the clinical response and elevation of peripheral cell counts. These data show that IVIG diminishes NK activity in vivo and that reduction of NK activity may be associated with clinical improvement in idiopathic thrombocytopenic purpura and autoimmune neutropenia. NK activity of lymphocytes obtained from healthy volunteers was reduced by the same concentrations of maltose or sucrose present in Gamimune or Sandoglobulin, respectively; IVIG preparations, however, were more inhibitory. The diminution of NK activity therefore may be related to two components of IVIG preparations, monomeric IgG and maltose or sucrose.