Acquired Immunity against Fungi

This chapter focuses primarily on four fungi, Candida albicans, Coccidioides immitis, Cryptococcus neoformans, and Histoplasma capsulatum, but also considers examples from other fungal pathogens. The primary goal in this chapter is to focus on the general principles involved in the acquired immune response to fungi. Major human fungal pathogens and medical conditions predisposing to invasive disease have been discussed in the chapter. For many bacterial and viral pathogens the importance of acquired immunity is evident from the observation that recovery from symptomatic infection results in long-lasting immunity. Nevertheless, for several fungal pathogens, serological skin reactivity surveys indicate that infections are common but clinical disease is rare, consistent with the development of acquired immunity. Hence, the experience with experimental vaccines against fungi indicates that acquired immunity can be protective against fungi and that both arms of the immune system can be effective depending on the antigen used and the fungal pathogen in question. For many fungal pathogens, the effective tissue response to invasion is granulomatous inflammation. Given that an extensive body of evidence indicates an important role for acquired immunity in host defense against fungal pathogens, it is nevertheless important to consider certain caveats with regard to the studies performed in this field.