Immunosuppression by cell wall antigens of Coccidioides immitis

Intranasal infection of BALB/c mice with Coccidioides immitis resulted in the induction of delayed-type hypersensitivity to coccidioidin within 9 days of infection and in the subsequent development of anergy. The acquired anergy was coincident with detection of circulating Coccidioides cell wall antigen and could be passively transferred to normal, syngeneic mice by intravenous injection with sera from infected donors. Suppression of T lymphocyte reactivity was also induced by injecting BALB/c mice intravenously with coccidioidin or a soluble extract of C. immitis cell walls. Suppression by intravenously administered antigen occurred via the activation of a splenic suppressor cell, as evidenced by suppressed T cell responses in recipients of spleen cells from antigen-injected donors. These collective results provide evidence for an immunosuppressive role of C. immitis cell wall antigens at levels comparable to those produced during the course of active coccidioidomycosis.