IL-10 NEUTRALIZATION AUGMENTS MOUSE RESISTANCE TO SYSTEMIC MYCOBACTERIUM-AVIUM INFECTIONS

In this contribution, we examined the involvement of the cytokine IL-1 0 in the progression of experimental murine Mycobacterium avium infect ions in susceptible BALB/c mice. Addition of anti-IL-10 antibodies in the supernatants of peritoneal macrophages infected with virulent M. a vium resulted in a significantly enhanced mycobacteriostatic activity of macrophages. In BALB/c mice infected with the B101 or B102 virulent M. avium strains, examination of the cytokine release profile in sple nocytes from infected mice showed that infection was associated with a n initial copious release of both IFN-gamma and IL-10. IL-10 productio n increased as the infection progressed, whereas IFN-gamma levels dimi nished. Infected mice were given repeated infusions of a rat mAb again st mouse IL-10 or rat IgM. Examination of IgM serum levels in anti-IL- 10-treated mice (infected or not) showed that depletion of endogenous IL-10 resulted in much decreased IgM levels. Results showed that infus ions of large dosages of the monoclonal anti-IL-10 resulted in a very significantly diminished bacterial growth in the spleens. These findin gs indicate that IL-10 may have a negative impact on resistance to M. avium infections, due, at least in part, to decreased macrophage activ ity.