ANTI-PR COLD AGGLUTININS RECOGNIZE IMMUNODOMINANT ALPHA-2,3-SIALYL ORALPHA-2,6-SIALYL GROUPS ON GLYCOPHORINS

Anti-Pr cold agglutinins (CAs) with the subspecificities anti-Pr-1h, - Pr-1d, -Pr-2, -Pr-3h, -Pr-3d, -Pr-M and anti-Sa CAs recognize immunodo minant N-acetylneuraminic acid (NeuN Ac) groups of tetra and/or trisac charides (O-glycans) of glycophorin. These O-glycans are sialylated in alpha 2,3- and/or alpha 2,6-linkages. Sa and most Pr antigens have be en inactivated by alpha 2,3-specific sialidases. Antigenicity was reco nstituted on desialylated glycophorin by alpha 2,3-specific Gal beta 1 ,3GalNAc-sialyltransferase indicating that alpha 2,3-linked NeuNAc gro ups are the immunodominant components of Sa and most Pr antigens. Some Pr antigens were resistant to alpha 2,3-specific sialidase and were n ot reconstituted by alpha 2,3-specific Gal beta 1,3GalNAc-sialyltransf erase, which indicates that alpha 2,6-linked NeuNAc group represents a n immunodominant component of some Pr antigens.