Recognition and Binding of Pathogenic Yeasts by Adhesion Molecules of Human Macrophages

The dimorphic zoopathogenic fungus, Histoplasma capsulatum (Hc) is distributed worldwide and causes a broad spectrum of disease in man and other mammals. The vast majority of infections are acquired by inhalation of spores or fragments of the mycelial phase that is present in contaminated soil. After lodging within the pulmonary alveoli, spores or mycelial fragments convert to the yeast form of Hc that causes all subseqent disease manifestations. During the initial phase of infection, patches of pneumonitis are observed that contain a predominance of macrophages (MO) within which the Histoplasma yeasts appear to multiply with a generation time estimated to be 9–11 hours.1–4 Thus, during primary infection of the lung, pulmonary MO presumably bind and phagocytose Hc yeasts in the absence of significant opsonizing activity thereby providing a favorable intracellular environment for multiplication of the organisms.