T cells from an HLA-DR11/DR12 responder were stimulated in mixed lymphocyte culture with cells carrying the DR1 antigen. After priming, T cells proliferated in response to both DR1-positive-stimulating cells and a peptide derived from a polymorphic region of the HLA-DR beta 1*0101 chain presented by responder's antigen-presenting cells (APC). The dominant epitope recognized by the primed T cells corresponded to residue 21-42 and was presented by the responder's HLA-DR12 antigen. The DR1 peptide-reactive T cells express T cell receptor V beta 3. The results demonstrate that allopeptides derived from the processing and presentation of donor major histocompatibility complex molecules by host-derived APC trigger alloreactivity. The frequency of T cells engaged in the indirect pathway of allorecognition is about 100-fold lower than that of T cells participating in the direct recognition of native HLA-DR antigen. However, indirect allorecognition may play an important role in chronic allograft rejection, a phenomenon that is mediated by the activation of T helper cells and of alloantibody-producing B cells.
Contribution of direct and indirect recognition pathways to T cell alloreactivity.
Z Liu, Y K Sun, Y P Xi, A Maffei, E Reed, P Harris, N Suciu-Foca; Contribution of direct and indirect recognition pathways to T cell alloreactivity.. J Exp Med 1 June 1993; 177 (6): 1643–1650. doi: https://doi.org/10.1084/jem.177.6.1643
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