For the in vivo studies, ten mice were used for each condition studied in each experiment. Differences in fungal burden were analyzed by Kruskal-Wallis test, and differences in survival were analyzed by log-rank test. The experiments were repeated at least twice, and similar results were obtained. (a) CFU determinations of Hc 14 days after infection of C57BL/6 mice with 5 × 10⁶ yeast. Bars are means of CFUs from four plates for each condition, and the error bars denote SD. The P values were generated by Kruskal-Wallis test comparing the median CFUs for mAb-treated mice with those for mice that received mAb 5C11 (control): *P < 0.001, **P < 0.01, ***P = 0.02. The experiment was repeated with similar results. (b and c) Histology of lungs from C57BL/6 mice pretreated with protective and nonprotective mAb and infected with 5 × 10⁶ yeast. (b) Representative image of lung from a mouse treated with protective mAb 9C7, showing peribronchiolar inflammation and intact alveoli. (c) The lungs of mice given control mAb had dense inflammatory infiltrates filling much of the alveoli. The original magnification was ×250, and the samples were stained with H&E. The inset in b shows Hc by Gomori’s methenamine-silver staining. (d) mAb to Hc prolongs survival of lethally infected mice. Mice were pretreated with 100 μg of mAb to Hc, nonspecific mAb (5C11), or PBS and infected with 1.25 × 10⁷ yeast. Compared with that of mice that received mAb 5C11 (control), survival was significantly prolonged with mAb to Hc (9C7, P = 0.002; 3B9, P = 0.004; 5B8, P = 0.007). (e) Preincubation of mAb 9C7 with Hc before lethal infection significantly prolonged survival compared with controls (9C7, P < 0.001). (f) Significant prolongation of the survival of lethally infected mice compared with controls (P < 0.001) was achieved by administration of mAb 9C7 before infection and treatment with subinhibitory concentrations of amphotericin B.