ABSTRACT
Knowledge of the immune response to natural infection with Neisseria gonorrhoeae is presupposition for the development of a gonococcal vaccine. Pili and protein I have gained importance for a subunite vaccine. A pilus vaccine proved to be ineffective in a field trial due to extensive pilus variability. According to an alternative strategy protein I may represent an important vaccine candidate for a gonococcal vaccine. To study the local and systemic, humoral immune response to N. gonorrhoeae cervical secretion, vaginal fluid and serum from prostitutes and family planning patients were compared by the use of a protein I ELISA. In local secretions and in serum patients in the study group showed significantly higher anti-protein-I-IgA-levels than patients in the control group. In cervical secretion immune response to an acute gonococcal infection consisted of a short lived, significant increase of anti-protein-I-IgA, while anti-protein-I-IgG showed a lower, but longer lasting significant increase. The course of the immune response in vaginal fluid reflected the immune response of cervical secretion at a lower level. In serum antigenic stimulus of a local gonococcal infection resulted in a significant but short lived protein I specific IgG immune response. In local infection with N. gonorrhoeae protein I represents a target antigen of the local and systemic immune response. Clear differences exist between local and systemic humoral immune response in the protein I reactive immunoglobulin class and in the course of reactivity. In the future it may be possible to define epitopes on protein I which induce protective immunity.