A recent seminar by Paul G. Thomas of the Department of Immunology, St. Jude Children’s Research Hospital, raised interesting questions about the nature of T-cell receptors (TCRs) that specifically respond to influenza virus and about the nature of TCRs in general. The title of the seminar was “TCR Repertoire Plasticity in Peripheral CD8 T Cells”. Dr. Thomas uses a murine model of immune responsiveness to flu virus and studies TCRs at the level of the single isolated T-cell. He reported that in this system allelic exclusion was complete for the TCR beta (TCRB) locus but that a single cell can express two TCR alpha (TCRA) chains (bi-allelic expression). Occasionally (~10% of isolated cells), this results in the expression of two distinct TCRs in the same cell. More often one of the two alleles is out of frame but transcripts from this out of frame locus may predominate over transcripts of the in-frame allele. There can be consequences of this mono versus bi-allelic TCRA expression on T-cell avidity, survival, proliferation, and functionality. More information about this and related work by Dr. Thomas on the naïve and immune anti-influenza T-cell response in the mouse can be found in Thomas PG et. al. Proc. Natl, Acad. Sci. 110:1839-1844, 2013.