Modified erythrocytes in indirect haemagglutination with Neisseria gonorrhoeae antigen.

Antigen prepared from gonococci by extraction with alkali has the ability to sensitize erythrocytes for agglutination or indirect haemolysis by corresponding antisera (Chanarin, 1954; Maeland, 1966; Thomas and Mennie, 1950). These indirect techniques have been used for the study of endotoxin preparations from gonococci. Endotoxins, however, require treatment with alkali before sensitization, except when the extraction procedure includes exposure of the antigen to alkali (Maeland, 1968, 1969b). Untreated erythrocytes were always used for sensitization with the alkali-treated antigens. Attempts have been made to use the indirect haemagglutination technique for detection of antibodies to gonococci, omitting alkali-treatment of the antigens. This report presents results which show that antigen present in saline extracts from gonococci has the ability to sensitize tanned or formalinized erythrocytes. Treatment of the antigen with alkali could then be omitted.