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Updated: Jun 17, 2026

Examination of Thymic Positive and Negative Selection by Flow Cytometry
Published on: October 8, 2012
CXCR4 acts as a costimulator during thymic beta-selection
Paul C Trampont1, Annie-Carole Tosello-Trampont, Yuelei Shen
1Carter Immunology Center, University of Virginia, Charlottesville, Virginia, USA.
Abstract:
Passage through the beta-selection developmental checkpoint requires productive rearrangement of segments of the T cell antigen receptor-beta gene (Tcrb) and formation of a pre-TCR on the surface of CD4(-)CD8(-) thymocytes. How other receptors influence betabeta-selection is less well understood. Here we define a new role for the chemokine receptor CXCR4 during T cell development. CXCR4 functionally associated with the pre-TCR and influenced beta-selection by regulating the steady-state localization of immature thymocytes in thymic subregions, by facilitating optimal pre-TCR-induced survival signals, and by promoting thymocyte proliferation. We also characterize functionally relevant signaling molecules downstream of CXCR4 and the pre-TCR in thymocytes. Our data designate CXCR4 as a costimulator of the pre-TCR during beta-selection.
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