ABSTRACT
In this chapter, the author explores the complexities of host resistance to this fungal pathogen and the disturbances of immunoregulation associated with infection. The mechanisms that prompt influx of polymorphonuclear leukocytes and granuloma formation are not completely understood. At present, two elements appear to be important. One is a serum-independent chemotactic factor released by Blastomyces yeasts and the other is an alkali-soluble fraction of cell walls from a virulent strain of B. dermatitidis yeasts. The functional properties of polymorphonuclear leukocytes may be modulated by several cytokines including colony-stimulating factor, lymphotoxin, tumor necrosis factor, gamma interferon, and other factor(s) contained within supernatants of resting or lectin-stimulated mononuclear cells. Conversely, optimal phagocytosis and killing of conidia and maximal killing of yeasts by human neutrophils required the presence of fresh serum. Heat-inactivation of serum or removal of serum from the medium sharply reduced the fungicidal activity of neutrophils.
