Iea. Flesch et al., EARLY INTERLEUKIN-12 PRODUCTION BY MACROPHAGES IN RESPONSE TO MYCOBACTERIAL INFECTION DEPENDS ON INTERFERON-GAMMA AND TUMOR-NECROSIS-FACTOR-ALPHA, The Journal of experimental medicine, 181(5), 1995, pp. 1615-1621
Interleukin 12 (IL-12) produced by macrophages immediately after infec
tion is considered essential for activation of a protective immune res
ponse against intracellular pathogens. In the murine Mycobacterium bov
is Bacillus Calmette-Guerin (BCG) model we assessed whether early IL-1
2 production by macrophages depends on other cytokines. In vitro, muri
ne bone marrow-derived macrophages produced IL-12 after infection with
viable M. bovis BCG or stimulation with LPS, however, priming with re
combinant interferon gamma (rIFN-gamma) was necessary. In addition, IL
-12 production by these macrophages was blocked by specific anti-tumor
necrosis factor alpha (TNF-alpha) antiserum. Macrophages from gene de
letion mutant mice lacking either the IFN-gamma receptor or the TNF re
ceptor 1 (p55) failed to produce IL-12 in vitro after stimulation with
rIFN-gamma and mycobacterial infection. In vivo, IL-12 production was
induced in spleens of immunocompetent mice early during M. bovis BCG
infection but not in those of mutant mice lacking the receptors for IF
N-gamma or TNF. Our results show that IL-12 production by macrophages
in response to mycobacterial infection depends on IFN-gamma and TNF. H
ence, IL-12 is not the first cytokine produced in mycobacterial infect
ions.