The popliteal lymph node graft-versus-host (GvH) reaction in the rat: a useful model for studying cell interactions in the immune response?

Simonsen (1962), in his comprehensive review article on GvH reactions, rightly emphasized the great applicability this reaction had in immunological research. A broader implication of GvH reactions than was perhaps expected was evident when the complex interactions between the donor cells the host's immune system were detected. In this review article, one aspect of the donor-host cell interactions is discussed. Using the popliteal lymph node GvH reaction as a model, it has been shown that the hyperplastic response in the lymph node is due to an accumulation and proliferation of cells almost exclusively of host origin. B cells are preferentially activated, and although mitogenic factors are released into the circulation during systemic GvH reactions, the interaction between donor TH cells and host B cells is probably of a more specific nature, involving only those B cells expressing MHC antigens to which the donor cells are able to react. This will presumably lead to a panclonal activation of host B cells with antibody production against a wide variety of antigens. Athymic nude rats are often surprisingly resistant to GvH reactions induced by allogeneic T cells, and this resistance can now be satisfactorily explained in terms of natural resistance mechanisms. Sometimes F1 hybrid rats are also resistant to GvH reactions induced by parental cells, indicating that this resistance may be restricted by non-codominantly inherited genes.