Strain differences in mouse cellular responses to Mycobacterium lepraemurium and BCG subcutaneous infections. II. Production of interleukins 2, 4, and 6 and of interferon-gamma by draining lymph node cells

C57BL/6, BALB/c, and CBA mice were infected either by Mycobacterium bovis BCG or by M. lepraemurium (MLM). Interleukins (IL) 2, 4 and 6 and interferon-gamma (IFN-gamma) were measured in the supernatants of draining lymph node cells (DLN) or control lymph node cells from uninfected mice, restimulated in vitro by the heat-killed infecting Mycobacterium. Uninfected lymph node cells did not develop any IL4, IL2, and IFN-gamma response to BCG and MLM. A significant IL6 response to BCG was observed, with CBA being the best producer and C57BL/6 the weakest. BCG-infected mice, which controlled the BCG infection, displayed variable patterns of lymphokine response to BCG according to the strain. C57BL/6 DLN cells produced more IL6 and IFN-gamma than IL2, whereas BALB/c mice produced more IL2. CBA secreted lymphokines with a similar pattern to that of BALB/c but in lower amounts. IL4 was not detected in any supernatant. MLM-infected mice displayed variable susceptibilities to MLM infection: C57BL/6 was resistant, BALB/c was susceptible after an initial efficient control, and CBA was fully susceptible. In each strain the lymphokine response to MLM was much lower than that triggered by BCG, but the pattern was similar. Thus, C57BL/6 DLN cells still produced significants amounts of IL2, IL6, and IFN-gamma, whereas BALB/c secreted IL2 alone and CBA did not produce any detectable lymphokine. IL4 was again not detected in any supernatant. The failure of BALB/c and CBA strains to develop IFN-gamma and IL6 responses to MLM might contribute to their low resistance to this infection.