Immunochemical studies on blood groups. LIV. Classification of anti-I and anti-i sera into groups based on reactivity patterns with various antigens related to the blood group A,B,H, Le a, Le b and precursor substances.

Quantitative precipitin assays were carried out with eleven anti-I and five anti-i cold agglutinin sera. Their reaction patterns with precursor substances and with certain antigens related to the A, B, H, Le(a), and Le(b) substances revealed at least six types of I and four types of i specificity. All of the I and i determinants appear to be represented in varying amounts on that fraction of the ovarian cyst precursor substance OG which was precipitated by 20% ethanol (OG 20% 2X). Only some of these determinants can be detected in the first periodate oxidation stages of A, B, and H substances, in cow substances, and in hydatid cyst fluid.