Hemagglutination inhibition studies of water soluble blood group substances recovered from the erythrocytes of classical Bombay Oh subjects.

Using ethanol and acetone fractionation to isolate soluble blood group substances from red blood cells, 'Bombay' Oh bloods were found to contain variable amounts of concealed H substance. The IgG variety of anti-H in 'Bombay' bloods has a greater affinity for these substances than the IgM variety of anti-H. Group O parents of 'Bombay' Oh subjects were found to have normal levels of H substance, indicating that individuals heterozygous for a recessive suppressor gene 'x' synthesize it normally. In the 'Bombay' family studied, Lewis determinants were abnormally expressed in two members. Lewis activity was detected in the soluble extracts of their red blood cells but not by the direct agglutination test. Further tests using known Le(a-b-) types are necessary to determine whether these findings are linked to the 'Bombay' Oh phenomenon.