Induction of reaginic (IgE) gonococcal antibodies in the rat by a common antigen of Neisseria gonorrhoeae

Abstract

An antigen (ZAB) common to Neisseria gonorrhoeae was prepared by stepwise elution of a crude gonococcal antigen (ZA) from columns of diethylaminoethyl cellulose employing 0.02 M phosphate buffers, pH 7.6, containing increasing concentrations of sodium chloride. Rats immunized with ZAB produced reaginic (IgE) antibody which cross-reacted with ZA prepared from eight gonococcal strains by the passive cutaneous anaphylaxis (PCA) test. Heatingof the sera at 56 °C for 4 h destroyed the PCA activity. The PCA activity of the anti-ZAB rat serum was removed after absorption with ZAB antigen or with rabbit anti-rat IgE but not after absorption with gonococcal lipopolysaccharide or with heat-killed or formalinized gonococci. Treatment of ZAB with trypsin or heating at 100 °C for 30 min destroyed or reduced the antigenic activity respectively. Further purification of ZAB by filtration through Sephadex G-100 gave a preparation (ZAB2) which contained the common antigen as shown by the cross-reactivity of anti-ZAB2 rat serum with seven strains of N. gonorrhoeae. Fraction ZAB2 contained material which had a molecular weight less than 13 700 and was associated with the presence of material absorbing at 260 nm. The results of this study indicate that a low molecular weight antigen, which appears to be protein in nature and associated with nucleic acid, is common to the gonococcus and is the main antigenic component inducing reaginic (IgE) antibody in the rat.