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.

Immunoglobulin A response against Gardnerella vaginalis hemolysin and sialidase activity in bacterial vaginosis.

OBJECTIVE: The aim of this study was to investigate the correlation between the immunoglobulin A immune response to Gardnerella vaginalis hemolysin and sialidase activity in vaginal fluids from patients with bacterial vaginosis. STUDY DESIGN: Nonpregnant women who were examined at a gynecologic clinic, in an age range of 18 to 62 years, were enrolled. The study population comprised 131 healthy volunteers, 32 women with bacterial vaginosis that was positive for immunoglobulin A to Gardnerella vaginalis hemolysin, 40 women with bacterial vaginosis that was negative for immunoglobulin A to Gardnerella vaginalis hemolysin, and 19 women with Candida vaginitis. Bacterial vaginosis was diagnosed by clinical criteria and Gram stain. RESULTS: Sialidase activity was present in 75% (54/72) of patients with bacterial vaginosis. Women having bacterial vaginosis and lacking a specific immunoglobulin A response had a significantly higher level of sialidase activity than patients who had an immune response against Gardnerella vaginalis hemolysin. Sialidase activity was detected in 87% (35/40) of the former subgroup of patients with bacterial vaginosis and in 59% (19/32) of women of the latter subgroup. No sialidase activity was measured in patients with candidiasis. Specificity of the assay for healthy controls was 95% (124/131 women without sialidase activity). CONCLUSIONS: Sialidases produced by Prevotella bivia and other microorganisms present in the microflora of patients with bacterial vaginosis are very likely a virulence factor not only by destroying the mucins and enhancing adherence of bacteria but also by impairing a specific immunoglobulin A immune response against other virulence factors such as cytotoxin from Gardnerella vaginalis.

Specific immune response against Gardnerella vaginalis hemolysin in patients with bacterial vaginosis.

OBJECTIVE: Our goal was to study the mucosal host response in bacterial vaginosis by evaluating the presence of a specific immune response elicited against the Gardnerella vaginalis hemolysin in vaginal fluids of patients and by verifying its correlation with usual criteria adopted to diagnose bacterial vaginosis. STUDY DESIGN: A total of 123 white women attending the gynecologic care unit for urogenital complaints or for screening of uterine malignancies (Papanicolaou test) aged from 20 to 60 years, nonmenstruating, were enrolled. Bacterial vaginosis was diagnosed by clinical criteria and a Gram stain score > 6. RESULTS: We performed the determination of the antibody response in vaginal fluid against the hemolysin produced by G. vaginalis, a common agent present in bacterial vaginosis. The purified G. vaginalis toxin was a suitable antigen for detecting the presence of an immune response in the vaginal fluids of patients with bacterial vaginosis regardless of the strain of G. vaginalis present. A specific immunoglobulin A response was detected in 60% of women with overt bacterial vaginosis (Gram stain score > 6) and in 18.5% of women with intermediate vaginal flora (Gram stain score 4 to 6). The specificity of the test was 91%. CONCLUSIONS: We found a correlation between the specific local immune response to G. vaginalis toxin and bacterial vaginosis. The highly purified form of the toxin is able to discriminate disorders from the opportunistic colonization by G. vaginalis.