Blood group I activities of synthetic oligosaccharides assessed by radioimmunoassay

Five synthetic oligosaccharides:

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related to precursors of the blood group A, B, H and Lewis antigens have been tested as inhibitors of 12 anti-I and 5 anti-i cold agglutinins by radioimmunoassay. In agreement with previous inhibition of precipitation and radioimmunoassays with oligosaccharides derived from ovarian cyst glycoproteins, the synthetic oligosaccharides 2 and 4 (but not 1, 3 and 5) were found to be effective inhibitors of anti-I Ma. The amounts of these two oligosaccharides required to give 50% inhibition of binding of anti-I Ma to a radioiodinated blood group I-active glycoprotein were 12 nmoles. A second anti-I cold agglutinin Woj which has close serological resemblance to anti-I Ma was also inhibited by oligosaccharides 2 and 4; the amounts required for 50% inhibition of binding were 16 nmoles. The remaining cold agglutinins were not significantly inhibited by any of these oligosaccharides at the highest doses tested, 106–183 nmoles.