Does the signal for the activation of T cells originate from the antigen-presenting cell or the effector T-helper?
The present view is that the antigen-presenting cell (APC) processes and presents simultaneously on its surface several different antigens that are displayed randomly (with respect to their being Self or Nonself) as peptide-MHC complexes. The naive T-cell interacting with its ligand on the APC is activated by "co-stimulation," the first step on the pathway to effectors. This view ignores the requirement for associative recognition of antigen (ARA) in mediating both the Self-Nonself discrimination and the regulation of effector class. The introduction of ARA as a requirement for these two decision functions highlights a critical role for the effector T-helper (eTh) and necessitates rethinking the contribution of the APC.
Cohn
Melvin
M
Conceptual Immunology Group, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA. cohn@salk.edu <cohn@salk.edu>
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology*; D015398:Signal Transduction / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology* / Q000378:metabolism