The efficacy of acquired humoral and cellular immunity in the prevention and therapy of experimental fungal infections.

In the past two decades, numerous studies have documented the importance of acquired immunity for host defense against invasive fungal infections. There is widespread consensus in the field of medical mycology that cellular immunity is critical for successful host defense against fungi. However, in recent years several studies have established the potential efficacy of humoral immunity in host protection against two major fungal pathogens: Candida albicans and Cryptococcus neoformans. For C. albicans, antibodies to mannan, proteases and a heat shock proteins have been associated with protection against infection. Furthermore, anti-idiotypic antibodies to antibodies recognizing killer toxin from Pichia anomala and mimicking natural anti-killer toxin receptor antibodies can protect against C. albicans and other microorganisms. For C. neoformans, antibodies to the capsular glucuronoxylomannan have been shown to mediate protection in animal models of infection. Vaccines that induce protective antibodies have been shown to protect against experimental C. albicans and C. neoformans infection. In contrast, humoral immunity has not yet been demonstrated to mediate protection against Coccidioides immitis. For C. immitis, protection against infection is thought to rely on T cell mediated immunity, and the emphasis is on identifying the antigens that stimulate protective cellular immune responses and several candidate vaccines have been identified. These results provide encouragement for the view that acquired immune responses can be mobilized for the prevention and treatment of fungal infections.