The effect of IgM-enriched human Ig and rabbit antithymocyte globulin on the stimulation of mononuclear cells

Whether IgM-enriched intravenous Ig (pentaglobin) is a useful adjunct treatment for graft versus host disease (GvHD) prophylaxis in allogeneic stem-cell transplantation is unclear. Clinical data with the use of a five-agent GvHD prevention regimen, including pentaglobin and antithymocyte globulin (ATG), are encouraging. In vitro both have been reported to modulate alloreactive T cells. We compared their inhibitory effect on the phytohemagglutinin-induced lymphocyte proliferation. ATG blocked the proliferation of lymphocytes at lower doses and much stronger than pentaglobin. The combination of both was not different from ATG alone. In pentaglobin, glucose used as stabiliser, caused the effect. Starting at a concentration of 40 mg/dL glucose, glucose alone showed a dose-dependent inhibition of phytohemaglutinin (PHA)-induced proliferation. For the in vivo application of pentaglobin, the results suggest that pentaglobin does not inhibit the proliferation of T cells.