Serological classification of anti-I sera.

Twelve anti-I sera were examined by means of broad panel of cells: OI, BI, OhI, Oicord, Oiadult, BI-F. Titration, fixation-elution, and haemagglutination-inhibition tests, and comparison of agglutination of untreated and neuraminidase-treated erythrocytes allowed to establish the specificity of the sera. For some sera the serological heterogeneity was revealed, which consisted in the following combinations of two or more kinds of specificity: anti-I-D plus anti-I-F, anti-I-D plus anti-i, anti-I-D plus anti-I-S, anti-I-D plus anti-I-F plus anti-I-S. Methodical problems of classification of anti-I sera are discussed.