Impairment of the mucosal immune system: IgA and IgM cleavage detected in vaginal washings of a subgroup of patients with bacterial vaginosis.

The integrity of the immunoglobulins in vaginal washings of patients with bacterial vaginosis was examined to answer the question of the lack of immune response against Gardnerella vaginalis cytolysin. Clinically diagnosed patients (n=100) were recruited and their vaginal washings examined by Western blotting. Many showed IgA and IgM partially or extensively degraded. According to the degradation pattern, the patients were subdivided into 4 subsets, from intact (score 0) to completely degraded IgA (score +3). Statistical analysis of the data showed a correlation between IgA degradation and absence of immune response to G. vaginalis cytolysin. The extent of IgA degradation correlated also with the sialidase (but not with the prolidase) activity level. All women showed intact IgG and human serum albumin and no trypsin-like activity. Patients with bacterial vaginosis having high sialidase activity and extensive IgA degradation in their secretions could incur more dangerous infections and adverse pregnancy outcomes.