γ/δCells in Fetal, Neonatal, and Adult RatLymphoid Organs

摘要

In the present study, we have analyzed the appearance and maturation ofγ/δT cells,recognized with a new mAb V65, in the central and peripheral lymphoid organs of fetal,neonatal, and adult Wistar rats. Cytofluorometrical analysis demonstrated the first V65+γ/δT cells in the thymus of 16-17-day embryonic rats, although by immunohistology, theywere identified only in 19-day rat embryos in both the cortico-medullary border and thymicmedulla. Phenotypically,γ/δthymocytes from fetal and neonatal thymus expressed CD3,CD2, and CD5, but only 60-80% were CD8+and approximately 40-50% expressed theαchain (p55) of the IL-2R. In the periphery, the immunohistological study identified for thefirst time ,γ/δT cells in the splenic white pulp and the gut of 21-day fetal rats, where theyoccurred within the epithelium as well as in the lamina propria. After birth,γ/δlymphocytes appeared in the skin, where they were present as dendritic epidermal T cellsin increasing numbers during postnatal life. Whereas theseγ/δT cells formed thepredominant T-cell population in the rat skin,γ/δT cells in peripheral lymphoid organs,BALT, or the gut only represented a minor T-cell population. These results are discussed incomparison toγ/δT cells of other vertebrate species.