Resistance of SJL mice to immunosuppression by antibodies.

Immunosuppressive antisera that specifically inhibit induction of tuberculin-type delayed hypersensitivity in mice to the antigens chicken conalbumin and methylated human serum albumin were compared for activity in CF-1, CAF1, and SJL mice. These contrasensitizing antisera were effective in CF-1 and CAF1 mice of various ages. But in SJL mice they were ineffective if the animals were older than 8 weeks and were only moderately effective if the animals were younger. The antibodies of these antisera responsible for specific immunosuppression could be absorbed onto adherent peritoneal exudate cells taken from DAF1 but not SJL mice. They could be eluted from the CAF1 cells at 56 degrees C. These results and other data that are discussed suggest that SJL resistance to immunosuppression by contrasensitizing antibodies is related to a macrophage abnormality. The results also help explain earlier findings that SJL mice are unusually easy to sensitize and unusually resistant to tolerogenesis. This strain of mice should be especially useful for studying the mechanisms of afferent immunosuppression in immunologic enhancement-like forms of tolerance.