Mannose binding lectin and C3 act as recognition molecules for infectious agents in the vagina

Area of Science:

• Immunology
• Microbiology
• Gynecology

Background:

• The cervicovaginal lavage (CVL) hosts a complex microbiome and immune environment.
• Bacterial vaginosis (BV) and vulvovaginal candidiasis (VVC) are common gynecological conditions with incompletely understood immune responses.
• Early complement components are crucial in innate immunity against pathogens.

Purpose of the Study:

• To investigate the presence and function of early complement components (C1q, mannose-binding lectin (MBL), C3) in the female genital tract.
• To determine if complement component levels or binding differ in patients with BV and VVC compared to healthy controls.
• To elucidate the role of MBL and C3 in recognizing common vaginal pathogens.

Main Methods:

• Quantification of C1q, MBL, and C3 levels in CVL using ELISA.
• Immunofluorescence analysis of clue cells and Candida for surface-bound complement components.
• Assessment of MBL binding to Candida in relation to pH.

Main Results:

• No significant differences in C1q, MBL, or C3 levels were found in CVL across study groups (BV, VVC, controls).
• C3 was detected on clue cells and Candida; C1q was undetectable.
• MBL was found on clue cells but not on Candida; MBL binding to Candida was pH-dependent (4.5-5.5).

Conclusions:

• MBL and C3 in the vaginal cavity function as recognition molecules for bacteria and fungi.
• MBL, but not C1q, binds to vaginal bacteria and fungi.
• The lectin and classical complement pathways likely have distinct roles in female genital tract immune defense.