The Pathogenesis of Experimental Pulmonary Histoplasmosis

A murine model of acute pulmonary histoplasmosis was employed to study the pathogenesis of the disease process by means of histopathology, bronchoalveolar lavage, and respiratory function tests. These studies were performed on C57BL/6 mice from 8 h to 8 wk after intranasal inoculation of 105 yeast forms of Histoplasma capsulatum and on age-matched control animals that received saline only. At Week 1, the histopathology was characterized by subacute inflammation consisting of polymorphonuclear leukocytes (PMN), lymphocytes, and macrophages that infiltrated the interstitium around small bronchioles and adjacent alveoli. At Weeks 2 and 4, the infiltrates were comprised predominantly of lymphocytes and macrophages; noncaseating granulomas were present at Week 2. Aggregates of lymphoid cells were prominent along the bronchial tree and in perivascular distribution. Those in close contact with bronchiolar epithelium resembled hyperplastic bronchus associated lymphoid tissue. Quantitative studies of cells in the ...