title: Effect of substitution on reactivity of B 512 dextran fractions with anti-B 512 dextran in heterologous passive cutaneous anaphylaxis.
abstract: The influence of type and degree of substitution of B 512 dextran fractions on reactivity with rabbit antibodies against unmodified B 512 dextran was studied on heterologous passive cutaneous anaphylaxis in guinea pigs. Low degrees of substitution, i.e. 1 substituent group per 7-30 glucose residues, affected reactivity with anti-dextran only slightly or not at all. This was shown for the following substituents: sulphate, carboxymethyl, phosphate, diethylaminoethyl, hydroxypropyl, butyryl, caprylyl, stearoyl, and fluoresceinoyl groups. With high degress of substitution, i.e. 1-3 substituents per 2 glucose residues, reactivity with anti-B-512-dextran is completely abolished for some substituents, and a new immunological identity conferred on the substituted dextran. Stongly charged groups like sulphate, carboxymethyl and diethylaminoethyl abolish reactivity with anti-B-512-dextran at relatively lower degrees of substitution than more neutral groups like methyl and acetyl. The anti-B-512-dextran represents a specific reagent for alpha-1,6-linked polyglucose, as evidenced by complete cross-reactivity with synthetic linear dextran; its specificity is emphasized by non-reactivity with alpha-1,6-linked synthetic manna, the monomeric residues of the two polymers differing only in position of the C-2 hydroxyl groups.
mesh_terms: D000818:Animals; D000906:Antibodies; D000918:Antibody Specificity; D003429:Cross Reactions; D003911:Dextrans / Q000031:analogs & derivatives / Q000276:immunology*; D006168:Guinea Pigs; D007106:Immune Sera; D007934:Leuconostoc / Q000276:immunology; D010323:Passive Cutaneous Anaphylaxis / Q000187:drug effects*; D011135:Polysaccharides, Bacterial; D011817:Rabbits
chemical_list: D000906:Antibodies; D003911:Dextrans; D007106:Immune Sera; D011135:Polysaccharides, Bacterial