The Final Maturation of at Least Some Single-Positive Cd4hiThymocytes Does Not Require T Cell Receptor–Major Histocompatibility Complex Contact

摘要: The majority (∼70%) of postselection CD4+ single-positive (SP) thymocytes are CD8loCD4hi. These cells express very low levels CD8, undetectable by flow cytofluorimetric (FCM) analysis, but sufficiently high to allow purification panning. Unlike the fully mature CD8−CD4hi thymocytes, which account for remaining ∼30% SP CD8loCD4hi functionally immature and short-lived unless they receive an unidentified maturation signal from thymus. In this study, we tested hypothesis that is provided a T cell receptor (TCR)–major histocompatibility complex (MHC) class II interaction. Using intrathymic transfer, show could complete their populate peripheral lymphoid organs in absence MHC (and I) molecules. Furthermore, mice devoid molecules, progeny was long-lived reactive allogeneic although numbers spleen mesenteric lymph node were ∼40–50% lower than those II+ 5 mo after transfer. Control experiments demonstrated surviving did not originate contaminating thymocytes. results demonstrate final maturation, proliferation, survival (up mo) at least some do require TCR–MHC They also indicate interaction(s) required development occurs before CD4hi stage development.