Soluble mannan and beta-glucan inhibit the uptake of Malassezia furfur by human monocytic cell line, THP-1.

The uptake of live and heat-killed Malassezia furfur HIC 3321, HIC 3343 and Candida albicans ATCC 10231 by human monocytic cell line, THP-1, was examined. THP-1 was differentiated by PMA for 7 days before use. The uptake of these yeasts by THP-1 was increased in a concentration-dependent manner of yeasts, and the uptake reached plateau level at the E/T (yeast/THP-1) ratio 5. In addition, a higher percentage of heat-killed cells than live cells was taken in THP-1. Yeast mannan and beta-1,3-glucan, random coiled conformer, inhibited the uptake of live and heat-killed M. furfur by THP-1, though dextran T-250, that is alpha-glucan, and schizophyllan (SPG), triple helix conformer of beta-glucan, did not. Interestingly, mannan inhibited the uptake of both types, live and heat-killed, of C. albicans, however, laminaran inhibited the uptake of heat-killed C. albicans alone. Opsonization of these yeasts with normal human serum enhanced the uptake of yeasts, although opsonization with heat-inactivated serum, the treatment at 56 degrees C for 30 min, did not enhance. These results suggested that live and heat-killed M. furfur was recognized by THP-1 through mannose receptor, beta-glucan receptor and complement receptor type 3 via the activation of alternative pathway of complement.