A biased Valpha24+ T-cell repertoire leads to circulating NKT-cell defects in a multiple sclerosis patient at the onset of his disease.

As natural killer T (NKT) cells have been implicated in the regulation of multiple sclerosis (MS), we investigated expression of the Valpha24JalphaQ canonical rearrangement in MS patients during relapses. We observed major changes in the entire blood Valpha24(+) T-cell repertoire. Seven of the eight patients showed a marked decrease in Valpha24(+) transcript number and a decrease in the diversity of the Valpha24(+) T-cell repertoire, with the exception of a few expanded clones. These perturbations, exacerbated in patient MS (A), led to circulating NKT cell defects.