Immunoreactivity of the fungal cell wall.

The cell wall is the major fungal structure involved in the interaction with the host and most of the immunological effects observed with intact fungal cells have been reproduced with cell-wall components. As a result of the exposure to fungal antigens, most individuals develop both cellular and antibody responses intended to limit the invasiveness or to eradicate the fungus from the infected tissues. However, a number of fungi including Candida albicans, Cryptococcus neoformans, Blastomyces dermatitidis, Coccidioides immitis, Trichophyton spp. and Histoplasma capsulatum can also induce T- and B-suppressive activities. A wide diversity of immunodominant cell-wall antigens for both cell-mediated and humoral responses have been identified in the most important fungal pathogens, although considerable differences exist in the information available at the molecular level among the different mycoses. Cellular responses require macrophage and Th1 activation, whereas humoral responses comprise the activation of the complement system and the induction of antibodies. The ability of fungal cell-wall components to elicit cellular or humoral immune responses has been traditionally used in the serodiagnosis of mycoses, the identification of fungal organisms and the development of vaccines for the prevention of mycoses. In the future, the analysis of such molecules will provide critical information in understanding the nature of host-fungus interactions.