The cells involved in cell-mediated and transplantation immunity in the normal outbred rabbit. X. The organ sources of the stimulator and responder cells in the mixed leukocyte culture reaction.

This investigation is concerned with the elucidation of the organ distribution of stimulator and responder cells in the one-way MLR (mixed leukocyte reaction). The organs investigated were the thymus, bone marrow, spleen, lymph nodes, appendix, sacculus rotundus, Peyer's patches and the circulation. Mitomycin-C treated bone marrow cells and WBC were used as stimulator cells to investigate, in a systematic fashion, the blastogenic responses of the responder cells of the allogeneic lymphoid organs. Responses occurred optimally on day 5 of culture and were dependent upon responder cell concentration. Peyer's patches and mesenteric lymph node cells responded to a greater extent than the cell of any of the other lymphoid organs. Rabbit WBC responded consistently in the one-way MLR, in contrast to the findings of other investigators. Cells of the thymus and bone marrow cultured individually or in combination did not respond. The cells of the different lymphoid organs were investigated as to their stimulator cell activity. Responder WBC or spleen cells were cultured with the mitomycin-C treated stimulator cells. On a per cell basis, the cells of the Peyer's patches, spleen and mesenteric lymph nodes were the most potent stimulator cells. There was no correlation between stimulating capacity and the percentage of stimulator cells bearing surface immunoglobulins. Thus, the stimulating capacity of these cells in the one-way MLR is not a reflection of, or dependent upon, surface immunoglobulins. A consistent finding was an MLR-like response of spleen cells and WBC cultured with autologous mitomycin-C treated Peyer's patches, sacculus rotundus or appendix cells.