T-cell receptor repertoire in healthy Sardinian subjects

Abstract

The T-cell receptor (TCR) Vβ gene usage of CD4 + and CD8 + T-cell subpopulations was evaluated by flow cytometric analysis and by CDR3 spectratyping in healthy subjects belonging to Sardinian population, which is ethnically homogeneous and genetically distant from all other Italian and Caucasoid groups. As described in healthy Caucasian subjects, we found a nonrandom Vβ gene usage and in some Vβ families a significant skewed reactivity toward CD4 + T cells. Moreover, different subjects showed expansions in some Vβ subfamilies, mainly in the CD8 + T cells. By CDR3 spectratyping analysis we found a significantly higher degree of skewness in the TCR Vβ repertoire of CD8 + than in that of CD4 + T cells. The similarity found in the TCR Vβ gene usage between the population examined and other Caucasoid groups suggest that the shape of the TCR repertoire is more influenced by rearrangement processes than ethnic background. However, genetic polymorphisms may condition the expression levels of some Vβs, determining the variability of the TCR repertoire between different populations. Finally, the profound perturbations evidenced in the CD8 + T cell subpopulation could be related to a different response to the antigenic stimulation between CD8 + and CD4 + T lymphocytes.