Candida albicans Is Phagocytosed, Killed, and Processed for Antigen Presentation by Human Dendritic Cells

SL Newman, A Holly - Infection and immunity, 2001 - Am Soc Microbiol
SL Newman, A Holly
Infection and immunity, 2001Am Soc Microbiol
Candida albicans is a component of the normal flora of the alimentary tract and also is found
on the mucocutaneous membranes of the healthy host. Candida is the leading cause of
invasive fungal disease in premature infants, diabetics, and surgical patients, and of
oropharyngeal disease in AIDS patients. As the induction of cell-mediated immunity to
Candida is of critical importance in host defense, we sought to determine whether human
dendritic cells (DC) could phagocytose and degrade Candida and subsequently present …
Abstract
Candida albicans is a component of the normal flora of the alimentary tract and also is found on the mucocutaneous membranes of the healthy host. Candida is the leading cause of invasive fungal disease in premature infants, diabetics, and surgical patients, and of oropharyngeal disease in AIDS patients. As the induction of cell-mediated immunity to Candida is of critical importance in host defense, we sought to determine whether human dendritic cells (DC) could phagocytose and degradeCandida and subsequently present Candidaantigens to T cells. Immature DC obtained by culture of human monocytes in the presence of granulocyte-macrophage colony-stimulating factor and interleukin-4 phagocytosed unopsonized Candida in a time-dependent manner, and phagocytosis was not enhanced by opsonization of Candida in serum. Like macrophages (Mφ), DC recognized Candida by the mannose-fucose receptor. Upon ingestion, DC killed Candida as efficiently as human Mφ, and fungicidal activity was not enhanced by the presence of fresh serum. Although phagocytosis ofCandida by DC stimulated the production of superoxide anion, inhibitors of the respiratory burst (or NO production) did not inhibit killing of Candida, even when phagocytosis was blocked by preincubation of DC with cytochalasin D. Further, although apparently only modest phagolysosomal fusion occurred upon DC phagocytosis of Candida, killing ofCandida under anaerobic conditions was almost equivalent to killing under aerobic conditions. Finally, DC stimulatedCandida-specific lymphocyte proliferation in a concentration-dependent manner after phagocytosis of both viable and heat-killed Candida cells. These data suggest that, in vivo, such interactions between DC and C. albicans may facilitate the induction of cell-mediated immunity.
American Society for Microbiology