In vitro immunological activities of the polysaccharide fraction from Haemophilus influenzae type a endotoxin
Infection and Immunity
Mild hydrolysis of Haemophilus influenzae type a lipopolysaccharide by ion exchangers in the presence of chloroform, to remove the lipid moiety, yelded 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
... ation 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] 106) and PS II (MW 104). Only PS I was found to act as a polyclonal B cell activator. EDTA treatment dissociated the polysaccharide into PS III (MW 106) and PS IV (MW 104), 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-molecularweight group (106) and an association of 104-MW aggregated units.