The Role of Ectopic Lymphoid Tissue in Allograft Rejection
The location of the immunologic response to an allograft is not known with certainty. However, organized collections of T cells, B cells and antigen presenting cells have been found in peripheral tissue, in close proximity to organs undergoing rejection. It is hypothesized that this tertiary lymphoid tissue may be a location in which activation of lymphocytes can occur, leading to rejection of an allograft. We report here that in a splenectomized aly/aly mouse, which is devoid of secondary lymphoid organs and will normally fail to reject an allograft, the presence of tertiary lymphoid organs is associated with graft rejection. We additionally find that tertiary lymphoid organs can act as lymph nodes, and can support effector and memory allograft rejection responses. It is demonstrated that ectopic lymphoid tissue in aly/aly mice will support the multiplication and transformation of transferred naïve CD4 and CD8 T cells into cells that display phenotypic markers characteristic of effector and memory lymphocytes. These results demonstrate that ectopic lymphoid tissue is associated with the loss of immunologic ignorance and is sufficient to enable graft rejection. This suggests that allograft rejection may take place within ectopic lymphoid tissue, and suggests that techniques to interfere with the development of this tissue might offer a therapeutic approach to preserving organ allografts.
School Location:USA - Connecticut
Source Type:Master's Thesis
Keywords:t lymphocytes allograft immunology b antigen graft rejection lymphoid tissue
Date of Publication:11/15/2006