Lymphocyte Fc gamma-receptor blocking antibodies in intravenous gammaglobulin preparations.

Various batches of intravenous gammaglobulin (IV-IgG) were found to contain antibodies with the capacity to block human peripheral blood lymphocyte receptors for the Fc region of IgG i.e., Fc gamma-receptors (Fc gamma Rs). The level of Fc gamma R-blocking produced was found to vary considerably from batch to batch and from lymphocyte donor to donor. IgG purified from normal human serum pooled from only 20 donors was also found to produce significant Fc gamma R-blockade. Analysis of the individual contributors to this normal IgG pool indicated that Fc gamma R-blocking antibodies may in fact be auto-antibodies.