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 Vdelta1+ subpopulation of gammadelta T cells. Surface expression of inhibitory receptors (IR) for HLA class I molecules have been mainly attributed to Vdelta2 + gammadelta T clones. In this study we have analysed the expression of these receptors in both subsets of gammadelta T peripheral lymphocytes. We studied 16 healthy controls and a reported case of homozygous TAP2 mutation with a marked increase of Vdelta1+gammadelta T cells. MICA/B presence in monocytes was also evaluated. In healthy subjects, the expression of CD94 and CD94/NKG2A was higher in the Vdelta2 + subset but cells bearing the IR ILT2 were found increased in the Vdelta1 +. The patient Vdelta2 + gammadelta T cells showed the same IR expression than normal controls, in contrast the Vdelta1+ 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 Vdelta1 + gammadelta T in TAP-deficient patients. MICA/B surface expression in monocytes was not shifted in gur patient. (C) 2003 Elsevier Science B.V. All rights reserved.