Inhibition of intracellular growth of Histoplasma capsulatum yeast cells by cytokine-activated human monocytes and macrophages

Abstract

Human monocytes/macrophages (MΦ) were infected with Histoplasma capsulatum yeast cells, and intracellular growth was quantified after 24 h of incubation in medium alone or in medium containing cytokines. Yeast cells multiplied within freshly isolated monocytes, cultured MΦ, and alveolar MΦ with intracellular generation times of 14.2 ± 1.4, 18.5 ± 2.1, and 19.9 ± 1.9 h (mean ± standard error of the mean), respectively. Monocytes and MΦ inhibited the intracellular growth of yeast cells in response to cytokine supernatant; maximum inhibition was obtained when cytokines were added to cell monolayers immediately after infection. Opsonization of yeast cells in normal serum or in H. capsulatum-immune serum did not affect the intracellular generation time of yeast cells in either control MΦ or cytokine-activated MΦ.