Candida albicans, Cryptococcus neoformans or Aspergillus fumigatus Induces an Antifungal Activity in Mouse Serum, which is Different from Transferrin

Abstract

ABSTRACT. It has been reported that administration of Candida albicans into mouse induces an antifungal activity in serum, which has been identified as transferrin. In the present study, we show that not only C. albicans, but also other fungus such as Cryptococcus neoformans or Aspergillus fumigatus similarly can induce an antifungal activity in mouse serum. This antifungal activity was inhibited by the addition of ferrous ion, indicating that the growth inhibition of C. albicans was due to deficiency of ferrous ion, which may be caused by transferrin. Indeed, addition of transferrin in an in vitro assay system using RPMI1640 culture medium inhibited the growth of C. albicans, C. neoformans or A. fumigatus. However, when C. albicans was grown in RPMI1640 medium with 10% fetal bovine serum (FBS), transferrin was unable to inhibit the growth of C. albicans, in sharp contrast, when C. albicans treated mouse serum was added instead of FBS, the growth of the organism was inhibited. Similar results were obtained when C. neoformans or A. fumigatus was used. Taken together, the results suggest that antifungal activity induced by C. albicans, C. neoformans or A. fumigatus was not due to transferrin but likely due to other unknown serum proteins, which may cut off the source of iron for the growth of these fungi.

Shared and distinct mechanisms of iron acquisition by bacterial and fungal pathogens of humans

“…Transferrin and lactoferrin are known to have an inhibitory effect on the growth of the pathogenic fungi A. fumigatus , C. albicans and C. neoformans (Sridhar et al, 2000 ; Ahluwalia et al, 2001 ; Lahoz et al, 2008 ; Almeida et al, 2009 ; Kornitzer, 2009 ; Okazaki et al, 2009 ). The mechanism of inhibition is probably due to iron sequestration by partially iron-loaded protein because additional studies have shown that these fungi can acquire iron from fully iron-loaded transferrin under specific conditions.…”