Human serum antibodies reacting with endotoxin from Neisseria gonorrhoeae.

The chemical composition and serological properties of endotoxin prepared from gonococci by extraction with aqueous ether have been described in previous reports (Maeland, 1969b, 1969c). Aqueous ether endotoxin contains one antigenic determinant of carbohydrate nature (determinant a) and another antigenic determinant of protein nature (determinant b) (Maeland, 1968, 1969a). A serological test system based on indirect haemagglutination technique has been described for each determinant (Maeland, 1969c). The b determinant has been shown to possess serological group-reactive properties and is also present in meningococci (Maeland, 1969d). The a determinant comprises several antigenic factors called a factors (Maeland, 1969d). One a factor was shared by all of 27 strains of gonococci examined, whereas other a factors occurred in different combinations among strains of gonococci. In recent years several reports on human antibodies to gonococcal antigens have appeared but few describe antibodies to antigens which have been isolated and characterized. A study of the reactivity of human sera with each of the determinants a and b of endotoxin from gonococci was therefore undertaken. This paper describes the results obtained with sixty human sera.