Analysis of Immature (CD4^–CD8^–) Thymic Subsets in T-Cell Receptor αß Transgenic Mice

Abstract

Introduction of a transgenic αß TCR (Vα₂, Vß_8.1) specific for lymphocytic choriomeningitis virus (LCMV), in the context of H-2D^b into the genome of C57BL/6 mice, has many effects on the development and selection of T cells in both the thymus and the periphery. These mice produce increased numbers of CD4^–8⁺ mature T cells, all of which express the transgenic TCR, and small numbers of CD4^–8⁺cells using endogenous TCRs are also produced. This study follows the intrathymic development of T cells in these TCR αß transgenic mice, in particular the earliest CD4^–8^– stages. As expected, the transgenic TCR is expressed on the cell surface at an earlier developmental stage than endogenous TCRs in nontransgenic littermate controls. Of the three major subsets expressing the heat–stable antigen (HSA), only the most mature, the CD25^–CD44^– expresses the transgenic TCR, and the earlier CD25^–CD44⁺ and CD25⁺CD44^– do not. Furthermore, in contrast to other TCRαßtransgenic lines, TCR γδ lineage cells appear to develop normally.