NEONATAL MOUSE CD4+ MATURE THYMOCYTES SHOW RESPONSIVENESS TO INTERLEUKIN-2 AND INTERLEUKIN-7 - GROWTH-INVITRO OF NEGATIVELY SELECTED V-BETA-6-EXPRESSING AND V-BETA-11-EXPRESSING CD4+ CELLS FROM (C57BL/6XDBA/2)F1 MICE

By three colour flow microfluorimetry, we have recently shown that neonatal mouse CD4 single positive thymocytes are a population of proliferating cells. Furthermore, analysis of CD4 + thymocytes from (C57BL/6 × DBA×2)F1 mice showed that they proliferate regardless of whether they express particular vyencoded TCR molecules (Vβ6 and Vβ11) that are undergoing Intrathymic deletion. In this report, cell culture experiments demonstrate that unstimulated neonatal CD4+ thymocytes from such mice proliferate in vitro In response to a combination of r-IL-2 and r-IL-7. Simultaneous three colour analysis of Vs TCR, CD4 expression, and DNA content of these cultured cells shows that Vβ6+, -8+, and -11+ cells grow equally well. Experiments where cells were cultured overnight in unsupplemented medium did not reveal preferential loss of negatively selected (Vβ6+ and Vβ11+) subpopulations of CD4+ cells. Taken together, these results suggest that IL-2 and IL-7 play a role In the Intrathymic proliferation of developing mature T cells. © Oxford University Press.