Immunochemical Studies on Blood Groups

Abstract

Summary The capacity of sugars of known structure to inhibit precipitation of type XIV antibody from two different samples of horse antiserum by blood group substances and their P1 fractions was assayed by the quantitative inhibition technique. Of the compounds tested, the β-galactosides, galactosyl 1 → 4 β-N-acetylglucosamine, galactosyl 1 → 3 β-N-acetylglucosamine and lactose were found on a molar basis to be the most potent inhibitors of precipitation by intact and mild acid treated preparations. The relative inhibitory capacity of β-galactosides was found to vary with the particular sample of horse anti-XIV employed and in addition varied for individual preparations when tested with the same antiserum. Inhibition findings do not permit a definitive conclusion regarding the linkage of terminal galactosyl substituents conferring type XIV cross reactivity to blood group substances. The liberation of greater amounts of galactose and N-acetylglucosamine from the P1 fraction by enzymatic treatment together with the increased potency of galactose over N-acetylglucosamine in inhibiting the cross reaction, suggests that the increased type XIV reactivity of the P1 fraction results from exposure of additional terminal β-galactosyl rather than N-acetylglucosamine end groups. Evidence that B P1 and type XIV cross reactive sites are conferred by different kinds of galactosyl groupings on the B substance was obtained from quantitative precipitin data showing the capacity to precipitate anti-B P1 to be independent of type XIV cross reactivity. Moreover, while enzymes of Clostridium tertium destroy type XIV reactivity they leave B P1 reactivity intact.