Allorecognition and T cell repertoire selection in severe combined immunodeficiency lacking HLA class II antigens.

In order to elucidate the role of HLA class II molecules in generation of self-nonself discrimination of human T cells, we have analyzed T cell functions in an HLA class II-negative severe combined immunodeficiency patient. Patient PBL expressed no HLA-DR, -DQ, and -DP antigens as judged by immunofluorescence using mAb, and failed to elicit MLR responses from unrelated controls. Patient PBL contained mature T cells (CD3 + TCRαβ + ) of the CD4 and CD8 subset, showing an apparently normal TCR diversity, as judged by use of anti-Vβ5, -Vβ6, -Vβ8, -Vβ12, and -Vα2 mAb