Presence of a novel subset of NKT cells bearing an invariant Vα19.1-Jα26 TCR α chain

CD1d-deficient (CD1d(-/-)) mouse lymphocytes were analyzed to classify the natural killer T (NKT) cells without reactivity to CD1d. The cells bearing a Valpha19.1-Jalpha26 (AV19-AJ33) invariant TCR alpha chain, originally found in the peripheral blood lymphocytes, were demonstrated to be abundant in the NK1.1(+) but not NK1.1(-) T cell population isolated from CD1d(-/-) mice. Moreover, more than half (11121) of the hybrid cell lines established from CD1d(-/-) NKT cells expressed the Valpha9.1-Jalpha26 invariant TCR alpha chain. The expression of the invariant Valpha19.1-Jalpha26 mRNA was absent in beta2-microglobulin-deficient mice. Collectively, the present findings suggest the presence of a second NKT cell repertoire characterized by an invariant TCR cc chain (Valpha19.1-Jalpha26) that is selected by an MTHC class I-like molecule other than CD1d. (C) 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.