CD45 molecule in γδ T-cell generation: Disruption of CD45 exon 6 does not affect Vγ3 dendritic epidermal T-cell development

Abstract

There are two distinct lineages of T cells: T-cell receptor (TCR) αβ-bearing cells (αβ T cells) and TCR γδ-bearing cells (γδ T cells). All of the αβ T cells and most subsets of γδ T cells develop in the thymus. It has been demonstrated that the protein tyrosine phosphatase CD45 plays a pivotal role in the intrathymic development of αβ T cells. Thymocyte maturation is arrested at the transitional stage from immature CD4+ CD8+ double-positive to mature CD4+ or CD8+ single-positive cells after CD45 exon 6 gene disruption. In this study, we examined whether Vγ3 dendritic epidermal T cells (DETC), a subset of thymus-dependent γδ T cells uniquely residing in the murine epidermis, are altered in the CD45 exon 6-deficient mice. In situ immunolabeling on epidermal sheets demonstrated that the CD45-deficient mice had a normal density and immunophenotype of Vγ3 DETC compared with the wild-type control mice. Reverse transcriptase polymerase chain reaction revealed that similar levels of Vγ3 TCR mRNA were present in the epidermis of CD45-deficient mice and wild-type controls. Flow cytometry demonstrated no significant difference in the proportion of Vγ3 T cells in the epidermis between the genotypes. In addition, Vγ2 T cells, another subset of γδ T cells, were also examined by flow cytometry. The frequency of Vγ2 T cells in lymph nodes was normal in the CD45-deficient mice. Our results indicate that although CD45 is crucial for the development of αβ T cells, this molecule is not necessary for the thymic maturation of γδ T cells, including Vγ3 DETC and Vγ2 T cells.