Mononuclear phagocytes freshly harvested from immunized animals restrict the intracellular growth of Histoplasma capsulatum, whereas the same cells maintained in culture for 48 hr do not. Experiments established that within the mixed cell population of the mouse peritoneal cavity the lymphocyte was the most likely mediator of the intracellular growth restriction observed. Partially purified lymphocytes, from the peritoneal cavity of mice immunized by sublethal infection, mediated the suppression of intracellular growth of the fungus in normal mouse macrophages in cell culture.

No abstract

Peritoneal exudate cells from immunized mice inhibit the intracellular growth of Histoplasma capsulatum. The lymphocyte is the mediator cell of this phenomenon. Lymphocytes from immunized animals are highly activated cells. Supernatants from cultures of immune lymphocytes or from cultures of mitogenstimulated lymphocytes did not arm macrophages from normal animals to inhibit the intracellular growth of H. capsulatum.

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The growth of Torulopsis glabrata was inhibited in glucose-peptone broth containing 10 to 20% normal human serum. Addition of iron to the medium diminshed the fungistatic effect. The intracellular growth of T. glabrata was remarkably restricted within mouse macrophages maintained in vitro, but this growth restriction was not caused by the limitation of iron imposed by the serum in the medium. The intracellular growth of T. glabrata within a very small percentage of the macrophages was not obviously related to the failure of lysosomal fusion to the phagosomes in those cells. The studies did not permit definite conclusions regarding the viability of the inhibited yeasts, but results suggested that a large portion of them survived. Potentially misleading artifacts of the technique for assessment of the intracellular behavior of the fungus were detected and are discussed.