Stability of IgG solutions, especially anti-D gammaglobulin, with special reference to measured proteolytic activity and degradation.

The stability of IgG solutions during the dating period can be predicted by measuring the degree of degradation after elevated storage conditions at +37 degrees C with added streptokinase. The measurement of proteolytic activity with a synthetic substrate correlates with the results obtained by SDS-disc gel electrophoresis and gel filtration. IgG molecules having Anti-D activity were observed to be essentially more sensitive to proteolytic degradation by plasmin than IgG molecules in general. It seems, therefore, that the methods which are suitable for the study of the stability of normal IgG preparations are not sufficient to predict the stability of anti-D gammaglobulin preparations.