Lactoferrin Protects Vaginal Cells from Candida, Helps Remove Them

OBJECTIVE: To study in vitro growth-inhibitory effects of activated lactoferrin (ALF) against vaginal isolates of Candida species and to measure the ability of ALF to block interactions of Candida albicans and Candida glabrata to the vaginal epithelial (VE) monolayer. STUDY DESIGN: In vitro effects of ALF on growth of C albicans and C glabrata in Sabouraud dextrose (SD) broth were measured as change in broth turbidity by microscale optical density assay. ALF was tested at 5 and 2.5 mg/mL concentrations against 105 yeast cell inoculum at 370 degrees C for 96 hours and compared with native lactoferrin and control (growth in broth without ALF). VE cells were isolated from human vaginal tissue biopsies to establish a functional monolayer for yeast interaction studies. ALF effects on Candida interactions with the VE monolayer were tested using 3H-thymidine-labeled yeast. Prophylactic (treatment prior to yeast inoculation onto VE) and therapeutic (treatment to detach VE-adherent yeast) potential of ALF (5 mg/mL) was evaluated against vaginal isolates of C albicans strain NTRL809A and C glabrata strain NTRL131G. RESULTS: Growth of Candida species indicated that a 105 yeast inoculum in SD broth proliferated to a stationary growth equilibrium (approximately 10(9) yeast cell density) in 18 hours (approximately 2 hours of generation time). ALF (5 mg/mL) elicited >96 hours of total stasis (100% growth inhibition) and was significantly effective against both Candida species (p < 0.0001). At 2.5 mg/mL dilution, ALF sustained total stasis activity to an average of 18 hours and 24 hours for C albicans (n = 5) and C glabrata (n = 5), respectively. Interaction studies indicated avid binding of C albicans (70 - 140 x 10(3) yeast) and C glabrata (50 - 75 x 10(3) yeast) per square centimeter of VE monolayer. ALF-treated VE showed significant blockade (p < 0.05) of yeast adhesion by 33% and 58% with C albicans and C glabrata, respectively. ALF treatment of yeast-VE complexes resulted in significant detachment (p < 0.05) of C albicans and C glabrata, by 58% and 51%, respectively. CONCLUSION: ALF is a natural fungistatic agent with potent yeast adhesion-blocking and detachment properties and is effective against the vaginal pathogens C albicans and C glabrata.