Human vaginal mucosal immune system: characterization and function.

OBJECTIVE: The mucosal immune system has been recognized as the first line of defense against foreign antigens. The limited information available on the mucosal immunity of the lower reproductive organs have restricted our ability to fight infections, especially, the sexually transmitted disease. The aim of this study was to characterize in-vitro the human vaginal lamina propria lymphocytes (VLPL), their cell surface phenotypes, and cellular function. METHODS: VLPL were isolated from human vaginal mucosa by enzymatic techniques. Cell surface characteristics were investigated by immunohistochemistry and flow cytometric analysis. Cellular immune function was evaluated by 3H-thymidine incorporation studies and ornithine decarboxylase (ODC) activity. RESULTS: Immunohistochemistry and flow cytometric analysis showed that the CD4/CD8 ratio of the human vaginal mucosa is reversed compared to the gut lamina propria lymphocytes (0.55 +/- 0.17). PHA and ConA mitogens enhanced VLPL thymidine incorporation, while PWM did not have any significant effect. Very high level of ODC activity was observed in VLPL after PHA stimulation. CONCLUSIONS: The human VLPL can be isolated, characterized, and respond to a mitogenic stimulus. We postulate that further analysis of the vaginal immune system will enhance our understanding of local defence mechanisms which will help in the development of new therapeutic modalities against vaginal infections.