STUDIES ON BLOOD GROUPS Ill . PROPERTIES OF PURIFIED BLOOD GROUP A SUBSTANCES FROM INDIVIDUAL

Some of the properties of blood group A specific substances from enzymatic digests of pools of hog stomachs have been presented in the preceding report (1). However, since it was known that not all hog stomachs show A activity (2), it was considered of interest to determine whether better products could be isolated from individual hog stomachs. When stomach linings from a number of individual hogs were each subjected to peptic digestion, and the digests purified by the phenol method of Morgan and King (3), it was found that preparations of high activity could be obtained from some but that others gave immunologically inactive products in the same yield and chemically indistinguishable from the active ones in all properties thus far studied. The active substances were found with one possible exception, within experimental error, to be of equal potency in precipitating anti-A and in inhibiting the hemagglutination of human A cells by anti-A. The other products were not active when tested by these technics and did not give rise to anti-A on injection into humans. Preparations from pools of hog stomachs which probably consist of mixtures of active and inactive substances, are of intermediate activity. A measure of the absolute purity of various active products can be obtained immunochemically by determining the proportion of the glucosamine of the added A substance precipitated by anti-A in the region of antibody excess.