A novel population of T-cell receptor αβ-bearing thymocytes which predominantly expresses a single V_β gene family

Recent studies have demonstrated that CD3 is expressed on a subset of thymocytes with a CD4^-CD8^- (double negative) phenotype^1,2. At least some of these cells bear the CD3-associated γδ T-cell receptor (TCR γδ)^3,4. Here we describe a second subset of double negative thymocytes which expresses CD3-associated αβ receptors (TCR αβ). Surprisingly, these cells express predominantly the products of a single V_β; gene family (V_β8). These CD4^-CD8^-, TCRαβ⁺ cells appear relatively late in ontogeny (between birth and day 5 of life) and thus are unlikely to be the precursors to the TCR αβ-bearing cells (CD4⁺CD8^- and CD4 ^-CD8⁺) already present at birth. They can be selectively expanded in vitro by stimulation with a monoclonal antibody to V _β8 (F23.1)⁵ in the presence of interleukin I (IL-1). We propose that this cell type is a unique T-cell population distinguishable from typical TCR αβ⁺ T cells by its CD4 ^-CD8^- phenotype and a restricted TCR V_β repertoire. Analysis of the unique phenotype of these cells suggests that they may represent the normal counterpart of the defective CD4^-CD8 ^- T cells found in the lpr autoimmune mouse.