Maturation of CD4−8−α/β TCR+T cells induced by CD2-stimulation in vivo and in vitro

Abstract

Newly generated (‘virgin’) rat thymocytes of the immature CD4⁺8⁺ double positive (DP) subset were treated in suspension culture for 2 days with the stimulatory pair of anti-CD2 monoclonal antibodies OX-54 and OX-55. Approximately 50% of the recovered cells had downregulated CD4 and CD8 and upregulated the T cell antigen receptor (TCR). CD2-stimulated, but not control thymocytes proliferated in response to TCR plus IL-2 stimulation. in vivo, postnatal injection of OX-54/55 led to a dramatic and selective Increase In functionally mature CD4⁻CD8⁻ double negative (DN) α/β-TCR^high thymocytes and peripheral T cells. These findings show that CD2 stimulation can promote T cell differentiation and suggest that DN TOR^high thymocytes can be generated from DP thymocytes via alternative pathways of T cell maturation.