Recipient elimination of allogeneic lymphoid cells: donor CD4(+) cells are effective alloantigen-presenting cells.
The encounter with allogeneic major histocompatibility complex (MHC) molecules expressed on donor leukocytes during transfusion of blood products has been shown to impact the recipient's immune responses in a number of settings. To better understand the responses induced by the transfer of allogeneic cells, a murine model was used to characterize the recipient responses that control the fate of the allogeneic lymphoid cells. Recipient CD8(+) cells could rapidly eliminate a large number of donor cells within 3 days after injection. When elimination responses were studied in the absence of CD8(+) cells, it was found that alloantibody production was the secondary elimination mechanism. Optimal recipient CD8(+) and B cell responses in this model required help from CD4(+) cells that could be provided by 3 different pathways. Although recipient CD4(+) cells could provide help when activated by direct recognition of allogeneic MHC class II molecules expressed on donor cells or by indirect recognition of processed alloantigen presented on recipient antigen-presenting cells (APCs), the most rapid recipient responses were generated by help provided by donor CD4(+) cells. Purified donor CD4(+) cells were also able to induce these rapid responses, indicating that activated donor CD4(+) cells expressing allogeneic MHC molecules were able to effectively stimulate responses by both recipient CD8(+) and B cells.
Department of Medicine, Rhode Island Hospital and Brown University, Providence 02903, USA. loren_fast@brown.edu
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D000818:Animals; D017951:Antigen Presentation; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000637:transplantation; D007519:Isoantigens / Q000276:immunology*; D017710:Lymphocyte Transfusion; D008285:Major Histocompatibility Complex / Q000276:immunology; D051379:Mice; D014184:Transplantation, Homologous
D007519:Isoantigens