title: In vitro immunological activities of the polysaccharide fraction from Haemophilus influenzae type a endotoxin.
abstract: Mild hydrolysis of Haemophilus influenzae type a lipopolysaccharide by ion exchangers in the presence of chloroform, to remove the lipid moiety, yielded a nontoxic and immunogenic polysaccharide fraction. This polysaccharide selectively triggered murine B lymphocytes in vitro: (i) it induced enhancement of thymidine incorporation and stimulated antibody secretion in cultures of normal and nude mouse spleen cells; (ii) it did not stimulate splenic T lymphocytes; (iii) the activation of B lymphocytes was not absolutely dependent on the presence of macrophages. Sepharose 4B gel filtration showed that this polysaccharide consisted at least of two fractions: PS I (molecular weight [MW] 10(6)) and PS II (MW 10(4)). Only PS I was found to act as a polyclonal B cell activator. EDTA treatment dissociated the polysaccharide into PS III (MW 10(6)) and PS IV (MW 10(4)), which was not reassembled after the addition of 0.02 M CaCl2. Both fractions PS III and PS IV were unable to stimulate B lymphocytes. The immunological active fraction of H. influenzae polysaccharide is PS I. This fraction consists of a high-molecular-weight group (10(6)) and an association of 10(4)-MW aggregated units.
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology; D004731:Endotoxins / Q000032:analysis*; D006193:Haemophilus influenzae / Q000276:immunology*; D008213:Lymphocyte Activation; D008934:Mitogens / Q000494:pharmacology; D011135:Polysaccharides, Bacterial / Q000032:analysis / Q000276:immunology* / Q000494:pharmacology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D004731:Endotoxins; D008934:Mitogens; D011135:Polysaccharides, Bacterial