T cell receptor dynamism of mucosal and systemic CD4+ T cells in the course of an immune response to Escherichia coli heat-labile enterotoxin.

The changes in T cell receptor (TCR) Vbeta expression, use, and clonality in mice orally challenged with Escherichia coli heat-labile enterotoxin (LT) were assessed. Use of the TCR Vbeta family and clonality were significantly changed at the single-cell level. In Peyer's patches of treated mice, use of TCR Vbeta6, Vbeta8, and Vbeta14 increased in CD4(+)CD44(+) T cells, compared with use in nontreated mice. On the other hand, use of TCR Vbeta1 and Vbeta8 was enhanced in splenic CD4(+)CD44(+) T cells. Intraepithelial lymphocytes isolated from LT-challenged mice showed expanded clonality (e.g., Vbeta1, Vbeta2, Vbeta9, and Vbeta18) and altered TCR Vbeta use (e.g., Vbeta15, Vbeta16, and Vbeta17). These findings reveal that oral administration of LT has distinct effects on mucosal versus systemic alphabeta T cells for induction of CD4(+) T cells with selected Vbeta use. This most likely reflects the function of LT as a mucosal modulator.