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Role of IL-12 in the Induction and Potentiation of IFN- gamma in Response to Bacillus Calmette-Guerin
Journal article   Peer reviewed

Role of IL-12 in the Induction and Potentiation of IFN- gamma in Response to Bacillus Calmette-Guerin

Michael A O'Donnell, Yi Luo, Xiaohong Chen, Akos Szilvasi, Sharon E Hunter and Steven K Clinton
The Journal of immunology (1950), Vol.163(8), pp.4246-4252
10/15/1999
DOI: 10.4049/jimmunol.163.8.4246
PMID: 10510362

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Abstract

Although Mycobacterium bovis bacillus Calmette-Guerin (BCG) has been accepted as the most effective agent in clinical use against superficial bladder cancer, its mechanism of action remains incompletely understood. A kinetic analysis in assessing the potential role of cytokines from BCG-stimulated murine splenocytes showed that IL-12 expression preceded that of other cytokines. Experiments subtracting endogenous BCG-driven IL-12 using neutralizing Ab or augmenting its activity with supplemental rIL-12 revealed not only that IL-12 plays a dominant role in IFN- gamma induction but also that it is normally dose limiting. A striking increase in IFN- gamma production could be generated in both mouse and human immunocompetent cell culture by the addition of even a small amount of rIL-12. Moreover, this same synergistic effect could be replicated during in vivo administration of BCG plus rIL-12 into the mouse bladder and was observed in a patient receiving intravesical combination therapy. In costimulation cultures, this synergy appeared to partially rely on IL-18 and IL-2 and could be down-regulated by IL-10. This suggests that a dynamic interplay between Th1 and Th2 cytokines is responsible for net IFN- gamma production. The ability of supplemental exogenous IL-12 to strongly shift this balance toward Th1 provides an immunological basis for using it in conjunction with intravesical BCG for bladder cancer immunotherapy.

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