Inhibition of T-cell expansion caused by inducible costimulator/B7h costimulation blockade in direct allorecognition pathway

Abstract

Objective: Inducible costimulator (ICOS)/B7h costimulation plays a crucial role in acute and chronic allograft rejection. To test the role of the ICOS signal in T-cell activation and expansion, we used ICOS-Fc-targeted B cells as donor antigen presenting cells to challenge the allogeneic response in vitro.

Methods: In vitro, the binding of ICOS-Fc with B7h on splenic B cells was confirmed by flow cytometry analysis. To evaluate the capacity of ICOS-Fc-targeted B cells to elicit an allogeneic response in vitro, we performed mixed lymphocyte reactions.

Results: The binding of B7h on splenic B cells by ICOS-Fc was confirmed at a saturating concentration of 100 μg/mL. Blockade of ICOS/B7h in direct allorecognition depressed proliferation of alloreactive T cells in vitro.

Conclusions: ICOS/B7h signal plays an important role in direct allorecognition, eliciting allogeneic responses in vitro.