In vitro modulation of proliferation and cytokine production by human peripheral blood mononuclear cells from subjects with various forms of coccidioidomycosis

Using peripheral blood mononuclear cells (PBMC) from individuals with or without coccidioidal delayed-type hypersensitivity (DTH), we examined and attempted to modulate the in vitro responses of PBMC from various donors to the coccidioidal antigen toluene spherule lysate (TSL). Among healthy DTH- positive donors, 100 ng of human recombinant interleukin-10 (IL-10) per ml suppressed both PBMC proliferation (P = 0.01) and gamma interferon (IFN-γ) and IL-12 production (for both, P < 0 05). In vitro proliferation and production of IFN-γ and IL-12 by PBMC were significant y higher in DTH- positive donors with active coccidioidomycosis than in healthy, nonimmune controls (P < 0.05) but not in active DTH-negative donors with or without human immunodeficiency virus infection (for both. P > 0.05). Human recombinant IL-12 increased IFN-γ production by PBMC from active, DTH- positive donors (P = 0.01) but not by PBMC from DTH-negative groups. For healthy DTH-positive donors, the median antigen-reactive cell frequency per 10⁵ PBMC was 3.7, compared to 1.7 in DTH-negative donors with active coccidioidomycosis (P = 0.03). These data indicate that the in vitro TSL response is highly dependent on coccidioidal DTH. Not only do PBMC from individuals with DTH appear to respond to TSL, but their response can be modulated in vitro with either IL-10 or IL-12. On the other hand, PBMC from DTH-negative individuals do not respond in vitro to TSL and their response is not modulable, suggesting a lack of antigen response.