Macrophages from protectively immunized mice have enhanced cytokine recall responses when stimulated with <i>C</i>. <i>neoformans ex vivo</i>.

(a-b) B cell knockout mice received an initial immunization with heat killed C. neoformans strain H99γ or C. neoformans strain H99γ and were allowed 70 days to resolve the infection. Mice were then treated with isotype control antibodies or depleted of CD4+/CD8+ T cells (a) and/or depleted of NK cells and neutrophils (b) prior to and during challenge with C. neoformans strain H99. Alternatively, macrophages were isolated from the lungs (c-e) and spleens (f-h) of the immunized mice, as well as from naïve mice, and cultured ex vivo with C. neoformans strain cna1Δ for 24 h. Supernatants were collected and analyzed for IL-2, IFN-γ, and TNF-α production. The survival data shown are from one experiment using 5–10 mice per experimental group. Cytokine recall data shown are means +/- SEM of 3–4 independent experiments using 20–25 mice per group. (*p p < 0.01 compared to media within the immunization group).