The minimal number of antigen‐major histocompatibility complex class II complexes required for activation of naive and primed T cells

摘要: Although previous studies have shown that 50-200 antigen-major histocompatibility complex complexes (Ag-MHC) are sufficient to stimulate significant secretion of interleukin (IL)-2 from MHC class II-restricted T cell hybridomas, there been no this nature on more physiologically relevant populations. In study we analyzed the ligand requirements for stimulation responses naive and previously primed cells derived receptor (TCR)-transgenic animals whose TCR is specific pigeon cytochrome c (PCC) 88-104 peptide presented by I-Ek. Primed were as sensitive reported requiring about 100 Ag-MHC synthesize readily detectable quantities IL-2, whereas required 15 times produce equivalent IL-2. Similarly, 40 a proliferative response, 400 complexes. contrast these results, showed similar when early events in activation pathway analyzed; i.e. down-modulation, CD69 CD25 expression, blast transformation. A further analysis IL-2 IL-2R expression indicated: 1) The first synthesis was detected at same concentration both cells, but made much concentrations increased; 2) expressed fivefold (R) than despite fact antigen dose-response curves with respect percentage expressing identical. These results suggest threshold number initiate activation, due inefficient IL-2R, engagement needed enable necessary amounts two molecules allow go through complete cycle replication.