Delayed-type hypersensitivity after immunization with ultrasonicated Mycobacterium lepraemurium in C3H and C57BL mice

Subcutaneous immunization with ultrasonicated Mycobacterium lepraemurium (MLMSon) in incomplete Freund's adjuvant (IFA) induced long-lasting skin reactivity with the kinetics of a tuberculin-type delayed hypersensitivity (DTH) reaction in both C3H and C57BL mice. The reactivity generally was stronger in C57BL than in C3H mice, and with increasing doses of MLMSon test antigen the local reaction increased more in C57BL than in C3H mice. Pretreatment of C3H mice with cyclophosphamide before immunization caused a shift in the dose-response curve so that the local reaction increased more with increasing doses of test antigen. Histological examination of the reaction elicited by MLMSon in immunized mice revealed a predominantly mononuclear cell infiltrate, and local reactivity could be transferred by immune cells but not by immune serum. The local reaction elicited by MLMSon exerted an adjuvant effect on the induction of DTH to sheep erythrocytes. Thus, MLMSon in IFA given subcutaneously induced stable DTH that conformed to the criteria for tuberculin-type DTH.