The pulmonary resident T lymphocytes (RPLs) expressing a nearly invariant T cell receptor gamma delta heterodimer (gamma delta TCR) migrate from fetal thymus to the lung epithlium, followed by RPL subsets expressing diverse sets of gamma delta TCRs after birth. However, it remains unclear whether the fetal type V gamma 6/V delta 1(+) RPLs are essential for gamma delta T cell repertoire formation in the lung epithelium. In this study, we found a marked decrease in the number of y delta RPLs at 4 weeks of age in V delta 1(-/-) mice and they predominantly expressed V gamma 6 and V delta 4 genes. The skewed diversity towards the V delta 4-(D delta 1)-D delta 2-J delta 2 junctional region was observed only in gamma delta RPLs from 4-week-old V delta 1(-/-) mice, compared with those from 8-week-old V delta 1(-/-) mice and the both ages of wild-type mice. These results suggest that the invariant V delta 1(+) T cells are crucial not only for optimal gamma delta T cell expansion but also for affecting the migration or microenvironment for other gamma delta T cells in the lung epithelium. (c) 2007 Elsevier Inc. All rights reserved.