Immunosuppression in experimental cryptococcosis in rats. Induction of afferent T suppressor cells to a non-related antigen

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Abstract
To demonstrate the nature of the suppressor cells elicited in rats infected with Cryptococcus neoformans and immunized with human serum albumin (HSA), spleen mononuclear (SpM) cells were fractionated through a nylon wool column. The adherent and non-adherent populations were collected and transferred to syngeneic rats. In all cases, the non-adherent or T-enriched cells adoptively transferred suppression to HSA, however, the suppressive effects of the non-adherent cells were never as great as those of the unpassed population of SpM cells. The fractions adherent to nylon wool also diminished the delayed-type hypersensitivity response to HSA although this was not significant, but glass-adherent cells did exhibit significant suppressor activity. Immunized, non-infected rats were used as donor controls. Furthermore, we showed that T-enriched-cells are sensitive to treatment with low doses of cyclophosphamide and that they bind HSA. These data indicate that immune suppression of the induction of the delayed-type hypersensitivity response to HSA in cryptococcosis can occur as a result of infection with C. neoformans, and that at least one mechanism involved is the induction of adherent and non-adherent suppressor cells. Characterization of the non-adherent cells indicates that they are Ts1 cells.