Some observations on "Bombay" bloods, with comments on evidence for the existence of two different Oh phenotypes.

Bloods from three individuals, one each of the phenotypes Oh-A, Oh-B and Oh-O have been studied. The work of Dzierzkowa-Borodej, et al.-10 was confirmed when it was shown that all three samples of Oh red blood cells had increased I antigen strength. The i, Sd-a, Le-a and Le-x antigens were not found to be increased. Attempts were made to adsorb and elute anti-A, anti-B and anti-A,B with the Oh red blood cells, using sera that contained high titered anti-I antibodies. This was done in the belief that previously reported positive results in such tests might be due to the high level of I on the Oh red blood cells, anti-I in the sera containing the ABO antibodies, and the Matuhasi-Ogata phenomenon. However, in no instance were we able to adsorb an ABO antibody onto the Oh red blood cells. Contrary to the report of others-10 the titers of anti-A, anti-B and anti-H in the sera of the three Oh individuals studied did not differ significantly. We suggest that the evidence from our findings and the work of others is sufficient to show that at least two forms of the Oh phenotype exist: one representing total suppression of H, A, and B antigens, and the other marked but not total suppression, with partial inhibition of antibody production.