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Activation-induced CD154 expression abrogates tolerance induced by apoptotic cells
Journal article   Peer reviewed

Activation-induced CD154 expression abrogates tolerance induced by apoptotic cells

Prajwal Gurung, Tamara A Kucaba, Thomas A Ferguson and Thomas S Griffith
The Journal of immunology (1950), Vol.183(10), pp.6114-6123
11/15/2009
DOI: 10.4049/jimmunol.0901676
PMCID: PMC2783861
PMID: 19841180

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Abstract

The decision to generate a productive immune response or tolerance often depends on the context in which T cells first see Ag. Using a classical system of tolerance induction, we examined the immunological consequence of Ag encountered in the presence of naïve or activated apoptotic cells. Naïve apoptotic cells induced tolerance when injected i.v.; however, previously activated apoptotic cells induced immunity. Further analysis revealed a key role for CD154, as tolerance resulted after i.v. injection of either naïve or activated apoptotic CD154 −/− T cells, while co-injection of an agonistic anti-CD40 mAb with naïve apoptotic T cells induced robust immunity. DC fed activated apoptotic T cells in vitro produced IL-12p40 in a CD154-dependent manner, and the use of IL-12p40 −/− mice or mAb-mediated neutralization of IL-12 revealed a link between CD154, IL-12, and the ability of activated apoptotic T cells to induce immunity rather than tolerance. Collectively these results show that CD154 expression on apoptotic T cells can determine the outcome of an immune response to Ag recognized within the context of the apoptotic cells, and suggest the balance between naïve and activated apoptotic T cells may dictate whether a productive immune response is encouraged.

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