Loss of rubella antibody from immune globulin treated with kaolin.

Sera and immune globulin (IG) preparations are customarily treated with kaolin before titration of their rubella hemagglutination-inhibiting (HI) antibody in order to rid them of nonspecific inhibitors of hemagglutination. The treatment was shown in this investigation to have no adverse effect on the antibody level of the sera but was found to remove considerable amounts of gamma-globulin from IG preparations. Evidence of this removal was obtained by serological tests, by spectrophotometric determination of protein concentration and by disc electrophoresis. In contrast to kaolin, heparin-manganese chloride (MnCl(2)) treatment of IG preparations had essentially no effect on the level of antibody globulin by all the criteria used. Heparin-MnCl(2)-treated IG lots were in these respects similar, if not identical, to their untreated counterparts. Since nonspecific inhibitors associated with the beta-lipoprotein fraction of serum are removed by the method employed to fractionate the IG samples, it seems unnecessary to treat the latter in any way for the HI test. No difficulty was encountered in this investigation with several untreated IG lots.