Cross-reactive red blood cell antigen-related substances in human leukocyte alpha interferon

Human leukocyte alpha interferon (IFN alpha) is a blood product. The possible contamination with blood-group antigens was studied using the double-immunodiffusion technique. With the exception of one lot received in 1980, which did not react, all three recent lots received in 1983 and 1984 reacted with 16, 20, and 21 of the 22 erythrocyte group-specific antisera tested. The only antiserum that did not react with any of the IFN alpha lots was anti-N. Preincubation of the IFN alpha with antisera abolished the precipitate lines seen in double immunodiffusion. Recombinant human alpha interferon used as a control did not show any reaction. Our results indicate the presence of red blood cell antigen-related substances in IFN alpha.