SLAP deficiency increases TCR avidity leading to a

Authors: Samantha F Friend Lisa K Peterson Ross M Kedl Leonard L Dragone

Publish Date: 2012/09/06

Volume: 55, Issue: 1-3, Pages: 116-124

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Abstract

How T cell receptor TCR avidity influences CD8+ T cell development and repertoire selection is not yet fully understood To fill this gap we utilized Srclike adaptor protein SLAPdeficient mice as a tool to increase TCR avidity on double positive DP thymocytes We generated SLAP−/− mice with the transgenic MHC class Irestricted TCR OT1 and SLAP−/− Vβ5 mice expressing only the βchain of the TCR OT1 transgene to examine the effects of increased TCR surface levels on CD8+ T cell development and repertoire selection In comparing SLAP−/− OT1 and Vβ5 mice with wildtype controls we performed compositional analysis and assessed thymocyte signaling by measuring CD5 levels In addition we performed tetramer and compositional staining to measure affinity for the cognate antigen ovalbumin OVA peptide presented by MHC Furthermore we quantified differences in αchain repertoire in SLAP−/− Vβ5 mice We have found that SLAP−/− OT1 mice have fewer CD8+ thymocytes but have increased CD5 expression SLAP−/− OT1 mice have fewer DP thymocytes expressing Vα2 signifying increased endogenous αchain rearrangement and more nonOVAspecific CD8+ splenocytes upon tetramer staining Our data demonstrate that SLAP−/− Vβ5 mice also have fewer OVAspecific cells and increased Vα2 usage in the peripheral Vβ5 CD8+ T cells that were nonOVAspecific demonstrating differences in αchain repertoire These studies provide direct evidence that increased TCR avidity in DP thymocytes enhances CD8+ T cell negative selection deleting thymocytes with specificity for cognate antigen an antigen the mature T cells may never encounter Collectively these studies provide new insights into how TCR avidity during CD8+ T cell development influences repertoire selectionThe authors thank E Treacy for technical assistance and P Marrack for critical reading of the manuscript The authors also thank Pamela Fink for generously donating B6 Vβ5 mice This work was supported by an NIH T32 Grant AI07405 SFF an Easton M Crawford Charitable Lead Unitrust Postdoctoral Fellowship LKP and a Within Our Reach grant from the American College of Rheumatology LLD

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