Skewed inhibitory receptors expression in a TAP2-deficient patient

Most of patients suffering from HLA class I deficiency due to mutations in TAP genes show a significative increase of the peripheral minor Vδ1+ subpopulation of γδ T cells. Surface expression of inhibitory receptors (IR) for HLA class I molecules have been mainly attributed to Vδ2+ γδ T clones. In this study we have analysed the expression of these receptors in both subsets of γδ T peripheral lymphocytes. We studied 16 healthy controls and a reported case of homozygous TAP2 mutation with a marked increase of Vδ1+ γδ T cells. MICA/B presence in monocytes was also evaluated. In healthy subjects, the expression of CD94 and CD94/NKG2A was higher in the Vδ2+ subset but cells bearing the IR ILT2 were found increased in the Vδ1+. The patient Vδ2+ γδ T cells showed the same IR expression than normal controls, in contrast the Vδ1+ subset presented a special pattern of very high expression of CD94 and ILT2 and low of CD94/NKG2A. The presence of a new IR poorly represented in healthy individuals could account for the selective increase of Vδ1+ γδ T in TAP-deficient patients. MICA/B surface expression in monocytes was not shifted in our patient. [Copyright &y& Elsevier]