Flow-cytometric method for the quantitation of the Fc function of intravenous immunoglobulin preparations

Objectives: We have developed and optimised a new flow-cytometric method fo r the measurement of the Fc function of intravenous immunoglobulin (IVIg) p reparations, which is important in predicting the effector function of immu noglobulin (ig) in such preparations. Materials and Methods: Ig was bound t o a monocytic cell line, THP-1 with Fc gamma RI and Fc gamma RII cell surfa ce receptors, and the bound Ig detected by FITC-conjugated F(ab)(2) fragmen t of rabbit anti-human IgG, Results: Validation studies showed that Ig boun d to the cell line through the Fc portion. The method detected alterations in Fc function caused by reduction with dithiothreitol or by storage. The m ethod was reproducible (CV<11%) and a limited comparison study showed that it correlated with the European Pharmacopoeia reference method. Conclusions : This technically simple method is suitable for the quantitation of the Fc function of Ig preparations. Copyright (C) 2000 S. Karger AG, Basel.