Alloreactive CD4 T cell activation in vivo: an autonomous function of the indirect pathway of alloantigen presentation.

摘要: Activation of alloreactive CD4 T cells occurs via the direct and indirect pathways alloantigen presentation. A novel TCR/alloantigen transgenic system was designed that permitted in vivo visualization cell priming through these pathways. When both presentation were intact, activation response to cardiac allografts rapid systemic by day 4 after transplantation, contrast seen skin allografts, which delayed until 10-12 days transplantation. Despite this there a paucity activated graft-infiltrating at posttransplantation. This finding suggests initial alloimmune responses within draining lymphoid organs. Furthermore, alloantigens derived from failed promote thymic negative selection developing thymocytes expressing TCR clonotype. In absence functional pathway, kinetics activation, anatomic localization, effector function remained unchanged. Overall, present study defines temporal characteristics demonstrates pathway proceeds optimally