NEWLY GENERATED THYMOCYTES ARE NOT REFRACTORY TO DELETION WHEN THE ALPHA-BETA-COMPONENT OF THE T-CELL RECEPTOR IS ENGAGED BY THE SUPERANTIGEN STAPHYLOCOCCAL ENTEROTOXIN-B

It has been reported that, following the initial expression of the T cell receptor (TcR) α/β, newly generated thymocytes pass through a developmental window characterized by ineffective coupling between the α/β and CD3 components resulting in resistance to deletion (negative selection). However, we now provide evidence that the TcR α/β on developing thymocytes is capable of delivering deletional signals in response to the superantigen staphylococcal enterotoxin B (SEB) as soon as the receptor is expressed. We also show that if TcR+ thymocytes are allowed to mature in organ cultures of embryonic thymus before SEB is added, they respond by proliferation giving rise to blast cells of CD4−CD8−, CD4+CD8− or CD4−CD8+ phenotypes. Copyright © 1990 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim