Abstract

Sera from 225 men and 140 women were examined by an indirect immunofluorescent antibody technique for antibody reactive with Neisseria gonorrhoeae. Antigonococcal IgM was demonstrated at a titre of greater than or equal to 16 in about 45% of infected, but in only 3% of non-infected, patients. Most of this antibody occurred in sera of patients who had been infected for less than 14 days. Antibody of the IgA class was found at a titre of greater than or equal to 16 in over half the infected, but in none of the non-infected, patients. IgG antibody reactive with the gonococcus was found in each infected patient at a titre of greater than or equal to 16 but in only 8% of controls. The mean log titre of this antibody was significantly higher in patients who had been infected for more than seven days than in those whose infection was of shorter duration.