Neutralization of IL-12 decreases resistance to Listeria in SCID and C.B-17 mice. Reversal by IFN-gamma.
Interleukin-12 (IL-12) is necessary for the production of IFN-gamma by NK cells during the generation of innate immunity and by T cells for the development of the Th1 response during specific cell-mediated immunity. Here we demonstrate that the endogenous production of IL-12 is critical to the survival of both immunocompromised SCID mice and normal C.B-17 control mice during a primary infection with Listeria monocytogenes. When IL-12 is neutralized in vivo, both strains of mice die at a normally sublethal dose of Listeria. Anti-IL-12 antibody-treated mice showed a decrease in macrophage I-Ad expression and an increase Listeria burden in the spleen. Furthermore, as has been demonstrated in vitro, these effects of IL-12 in vivo were predominantly regulated through the production of IFN-gamma. Administration of IFN-gamma simultaneously with neutralizing antibodies to IL-12 restored macrophage I-Ad expression, limited the spread of the infection, and resulted in the survival of SCID mice. Thus, IL-12 is critical for resistance to infection with Listeria monocytogenes, and this resistance is mediated through stimulation by IL-12 of IFN-gamma production. Concomitant experiments confirmed that anti-TNF antibodies also resulted in uncontrolled infection and a decrease in macrophage I-Ad expression. However, administration of IFN-gamma restored the levels of I-Ad in macrophages but did not limit Listeria growth.
Tripp
C S
CS
Department of Pathology, Washington University School of Medicine, St. Louis, MO 63110.
Gately
M K
MK
Hakimi
J
J
Ling
P
P
Unanue
E R
ER
D000818:Animals; D007371:Interferon-gamma / Q000096:biosynthesis / Q000494:pharmacology*; D018664:Interleukin-12; D007378:Interleukins / Q000502:physiology*; D008088:Listeriosis / Q000276:immunology*; D051379:Mice; D016513:Mice, SCID; D011994:Recombinant Proteins
D007378:Interleukins; D011994:Recombinant Proteins; D018664:Interleukin-12; D007371:Interferon-gamma