Immunochr mur r ~ ~ . Vol 15. pp 733-736 ‘c ‘Pergamon Prrs Ltd 1978. Prmted m Great Brltam BLOOD GROUP I ACTIVITIES OF SYNTHETIC OLIGOSACCHARIDES ASSESSED BY RADIOIMMUNOASSAY TEN FEIZI*‘, EDWIN WOOD’, CLAUDINE AUGcL, SERGE DAVID2 and ALAIN VEYRII?RES Abstract l-ive synthetic oligosaccharides: GlcNAc[~l+i )Galf (oligoaacchandc 1) Gal/i1 -4GlcNAc/ll-6, ,Gal (ollgosaccharide 2) Gal/i1 -3GlcNAc~~l+.i’ Gal/i1 -3GlcNAc/il +3Gal (oligosaccharide 3) Gal/,‘1 +4GlcNAc/~I +6Gal (ohgosaccharide 4) Gal/,1 +3GlcNAc/~l+6Gal (oligosaccharide 5) related to precursors ofthe blood group A. B, H and LCHIS antigens have been tested as inhibitors of I2 antI- nnd 5 anti-i cold agglutinins by radioimmunoassay. In agreement with previous inhibItion of preclpitatwn and radummunoassays with oliposaccharides derived from ovarian cyst glqcoproteina. the a)nthctlc oligosaccharides 2 and 4 (but not I, 3 and 5) were found to be rlTecti\e inhibitors of anti-l Mn. The :lrnotm1\ of these two ohgosaccharides required to give So”,, inhihltmn of bindlnp of anti-l Ma to a radiolodinated blood group l-active glycoprotein were I? nmolcs. A second anti-1 cold agglutinin WOJ which has claw serological resemblance to anti-1 Ma wah also Inhibited bq oligosxchnrldcs 7 and 4. the amounts rcqulred for 50 “,, inhibition 01‘ bmding were I6 nmoles. The remaining cold agglutlnins were not slpnilicantl) inhlbited by any 01‘ these oligosacchnrides itt the highest doses tebted. I O&l X3 nmoles. The human anti-1 and anti-i cold agglutinins are monoclonal or oligoclonal IgM antibodies best known as autoantibodies reacting preferentially with adult (anti-I) or cord (anti-i) erythrocytes (Race & Sanger. 1975; Feizi, 1977). Although the I and i antigens are best known as cell surface antigens. their expression on ovarian cyst glycoproteins lacking blood group A, B, H and Lewis activities, and their unmasking after partial degradation of ABH active glycoproteins (Feizi et al.. 1971a,h; Feizi & Kabat, 1972), certain gangliosides (Fiezi et al., 1978) and glycolipids (Niemann rt trl.. 1978) have indicated that they represent commonly occuring polysaccharide core structures. The chemical characterization of these antigens is of considerable interest not only because they are targets of autoantibodies in human disease (Dacie, 1962) but because of their accumulation in certain human adenocarcinomas (Feizi et cd., 1975; Feizi, 1978) and their occurrence on the major erythrocyte transmembrane protein, Band 3 (Childs ct al., 1978). Quantitative precipitin assays with a variety of human and animal glycoproteins (Feizi rt ul., 1971~: -____ *To whom correspondence should be addressed. -;- Abbr-e\intionb uxxl: Gal. I) galactow. GlcNAc. ?- acetamldo ?-deoxy-I,-glucose: Cu. ceramide. Fclri & Kabat. 1972) and haemagglutination studies with adult and cord erythrocytes (Dzierzkova-Borodej r/ (II.. 1975) have shown considerable differences in the reactivities of the anti-1 and anti-i antibodies of individual patients and it has been suggested that there exist several types of I and i antigenic determinants. Inhibition of precipitation assays with oligosac- charides from I-active ovarian cyst glycoproteins have shown that one anti-1 cold agglutinin (from patient Ma) recognizes the sequence Gal[jI +4GlcNAc/~l+6- (Feizi et ~1.. 1971h) which is one type ot oligosaccharide chain found on the core of A. B, H and Lewis active glycoproteins (Lloyd & Kabat. 1968: Aston (11 ul.. l968), glycolipids (Watanabe rr ul., 1975) and milk oligosaccharides (Kobata & Ginsburg. 1972). Another anti-1 antibody (from patient Step) and an anti-i antibody (from patient The) were not inhibited in this structure. By radio- immunoassays and haemagglutination inhibition. it has been recently shown that the glycolipid G a 1 /i I -4GlchAc/il +?Gal/il -4GIcNAc//l + 3&l/11 +4Glcl- I C‘er (lacto-l~-~~or--hex~~~~sylceramide) when incorporated into cholesterol,Iecithin lipsomes, is a potent inhibitor of the anti-i cold agglutinins of patients Tho. McDon. Den. Hog and McC: it also Inhibits the anti-1 cold apglutinin Step and to a lesser extent anti-1 Da and Phi but not anti-1 Ma (Niemann 01 (I/.. 197X). This 733