Outer membrane protein III of Neisseria gonorrhoeae: variations in biological properties of antibodies directed against different epitopes

Monoclonal antibodies (mAbs) have been raised to gonococcal outer membranes. A panel of six mAbs was identified by several criteria as reacting with outer membrane protein III (P.III). Competitive radioimmunoassays showed that the mAbs could be grouped into three pairs recognizing different epitopes on P.III. These epitopes are equally present on all pathogenic Neisseria. The mAbs demonstrated differing protective effects in model systems. Those directed against one epitope were particularly effective in protecting Chang conjunctiva epithelial cells against gonococcal challenge. mAbs against this epitope and another promoted complement-mediated bactericidal activity, while those directed against the third epitope were ineffective. Thus the biological effects of mAbs directed against P.III vary according to the epitope recognized.