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Updated: Aug 25, 2026

Examination of Thymic Positive and Negative Selection by Flow Cytometry
Published on: October 8, 2012
An alternative to current thinking about positive selection, negative selection and activation of T cells
1The Salk Institute for Biological Studies, Conceptual Immunology Group, La Jolla, CA 92037-1099, USA. cohn@salk.edu
Abstract:
Given that recognition by the T-cell receptor (TCR) of allele-specific determinants on major histocompatibility complex (MHC)-encoded restricting elements (Rs) is germline encoded, whereas recognition of peptide (P) is somatically encoded, two combining site repertoires, anti-R and anti-P, are implied. As a consequence, the three pathways of T cells, positive selection, negative selection and activation, must be signalled by qualitatively distinct interactions engaging the TCR. These are spelled out as they provide an alternative to the current thinking that these pathways depend on affinity-based quantitatively distinguishable interactions.
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