Characterization of various anti-Pr cold agglutinins.

Forty -one samples of anti-Pr cold agglutinins (CA) were studied. The titers ranged from 4 to 32,000. As is the case with cold agglutinins of other specificities, immunoglobulin class M and k-type light chains predominated with anti-Pr CA. On the other hand, the few IgM lambda, IgG, and IgA found were associated preferentially with anti-Pr specificity. All anti-Pr CA were inhibited by human red cell membrane sialoglycoproteins. On the basis of an increased inhibition by sialoglycoproteins after periodate oxidation and carbodiimide treatment, respectively, three anti- Pr2 and five anti-Pr3 were found. Among 24 anti-Pr1 CA subclassified on the basis of agglutination with dog red cells, six were anti- Pr1h , 16 were anti- Pr1d , and two did not fit into the subclassification. Similar to the anti- Pr1h , - Pr1d subclassification, anti-Pr3 CA could be subclassified into anti- Pr3h , - Pr3d . Three anti-Pra examples were found. None of the anti-Pr CA was inhibited by N-acetylneuraminic acid; some (5/35) were inhibited by sialyllactose, NeuAc alpha 2-3 2-6 Gal beta 1-4Glc, in high doses (5.0-20.0 mM).