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Updated: Jul 13, 2026

A TIRF Microscopy Technique for Real-time, Simultaneous Imaging of the TCR and its Associated Signaling Proteins
Published on: March 22, 2012
In vivo cross-priming of MHC class I-restricted antigens requires the TAP transporter
A Y Huang1, A T Bruce, D M Pardoll
1Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Abstract:
Recent in vitro evidence suggests two alternative mechanisms by which bone marrow-derived APCs may process exogenous antigens for presentation to CTL in vivo, a phenomenon termed cross-priming. Although in vitro studies have suggested that both TAP-dependent and TAP-independent pathways exist, we have now demonstrated an absolute requirement for a functional TAP for cross-priming to occur in vivo. Bone marrow chimeras reconstituted with marrow from TAP-defective donors develop functional CD8+ CTL, but have APCs with disrupted TAP function. In such chimeras, in vivo priming of naive CTL was observed when antigen was targeted to the ER in a TAP-independent fashion, but cross-priming could not be demonstrated. These results support the TAP-dependent mechanism of cross-priming.
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