Transfer of cell-mediated immunity to Paracoccidioides brasiliensis in hamsters with dialysable leukocyte extracts.

Dialysable leukocyte extracts (DLE) were obtained from lymph nodes and spleen cells of hamsters immunized with Paracoccidioides brasiliensis (immune DLE) or from non-immunized hamsters (non-immune DLE). Sensitivity to P. brasiliensis antigen (PbAg) was transferred by immune DLE to normal recipient hamsters and could be detected by the macrophage migration inhibition (MIF) assay on day three and by a positive skin test to PbAg on day seven after DLE inoculation. This reactivity persisted for 120 days. The specificity of DLE was studied by inoculation of immune or non-immune DLE into normal hamsters and transfer was evaluated 7 days later by the MIF assay and by skin tests to PbAg, Candida albicans antigen (CaAg), sonically treated bacille Calmette-Guérin (BCG) (SBCG) and ovalbumin (OVA). The immune DLE recipients showed a reactivity to PbAg that was significantly stronger than that of the nonimmune DLE recipients although both groups of recipient animals showed reactivity to CaAg and SBCG. The results suggest that both DLE preparations contain a non-specific antigen augmenting factor. This factor may stimulate the minimal background response to the antigens in nonimmunized recipient hamsters.