| Abstract: | The circulating T cell pool of an MHC class II-deficient patient was shown to lack the MHC class II-specific T cell functions. This was demonstrated by the absence of MHC class Il-specific alloreactive T cells and a substantially decreased number of circulating CD4+ lymphocytes. The patient's T cells did respond to an allostimulus, although the restriction pattern of this reaction remains speculative. The function and distribution of peripheral T cell subsets from the patient resemble findings in MHC class II-deficient mice, which also lack interaction of T cell precursors with MHC class Il-bearing accessory cells during thymic differentiation. Our data support the concept that Tcell differentiation in humans is similar, and that the human MHC-restricted Tcell repertoire depends on prior interaction of T cell precursors with self MHC. |
