Affiliation:
1. From the Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710
Abstract
Antigen (Ag)-driven selection of helper T cells (Th) in normal animals has been difficult to study and remains poorly understood. Using the major histocompatibility complex class II– restricted murine response to pigeon cytochrome c (PCC), we provide evidence for both preimmune and Ag-driven selection in the evolution of Ag-specific immunity in vivo. Before antigenic challenge, most Vα11+Vβ3+ Th (70%) express a critical complementarity-determining region 3 (CDR3) residue (glutamic acid at TCR-α93) associated with PCC peptide contact. Over the first 5 d of the primary response, PCC-responsive Vα11+Vβ3+ Th expressing eight preferred CDR3 features are rapidly selected in vivo. Clonal dominance is further propagated through selective expansion of the PCC-specific cells with T cell receptor (TCR) of the “best fit.” Ag-driven selection is complete before significant emergence of the germinal center reaction. These data argue that thymic selection shapes TCR-α V region bias in the preimmune repertoire; however, Ag itself and the nongerminal center microenvironment drive the selective expansion of clones with preferred TCR that dominate the response to Ag in vivo.
Publisher
Rockefeller University Press
Subject
Immunology,Immunology and Allergy
Cited by
141 articles.
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