Corynebacterium parvum- and Mycobacterium bovis bacillus Calmette and Guerin-induced granuloma formation in mice lacking CD4 and CD8

Granuloma formation is a T-cell-dependent inflammatory response that is imp ortant in the host defense against intracellular bacteria. The role of CD4 and CD8 molecules in the development of Corynebacterium parvum- and Mycobac terium bovis Bacillus Calmette and Guerin (BCG)-induced granulomas was exam ined in CD4/CD8 knockout (KO) mice. CD4/CD8 KO mice developed a greater gra nulomatous response to heat-killed C. parvum and heat-killed BCG than did c ontrol mice. Thus, granuloma formation is not dependent upon the presence o f CD4 and CD8. On the other hand, CD4/CD8 KO mice challenged with live BCG; showed initially fewer and smaller granulomas but later more and larger gr anulomas than control mice. CD4/CD8 KO mice had a greater BCG load than con trol mice. The absence of CD4 and CD8 therefore impaired the host defense a gainst infection with BCG. alpha beta T-cells were present in the granuloma s of both GD4/CD8 KO and control mice in similar numbers. Also the producti on of IFN-gamma mRNA was similar in the two groups. In conclusion, CD4 and CD8 are not essential to the granulomatous response against C. parvum and B CG, but contribute to the host defense against live BCG; infection. (C) 199 9 Academic Press.