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Lymphocytes that recognize class I alloantigens (class I T cells) are able to lyse appropriate target cells and release lymphokines in vitro. However the relative contribution of these activities to biological, in vivo functions of these cells is unclear. It is possible to discriminate between these activities using cyclosporine (CsA). CsA inhibits lymphokine release from class I T cells but has no effect on their cytotoxic activity. The in vivo function of class I T cells is analyzed using 2 models; the local GVHR induced by the transfer of sensitized T cells to the foot-pad and islet allograft rejection induced by the passive transfer of sensitized T cells. Both reactions may be mediated by class I T cells. CsA inhibits the in vivo functions of the class I T cells in both systems--hence, these functions appear to be lymphokine-dependent. This demonstrates the ambivalence of this T cell subset in relation to biological function; the cells express direct cytotoxic activity and producing lymphokines. The alloreactivity of the class I T cells is dependent upon the latter activity.

Using preliminary in vitro culture in an oxygen-rich atmosphere to facilitate survival of the graft, long term survival (greater than 100 days) of mouse pancreatic islet allografts was obtained subsequently in non-immunosuppressed diabetic animals. When anti-donor alloantiserum was transferred to these animals, the grafts were not rejected despite the fact that circulating cytotoxic antibody was demonstrated up to 7 days after injection of alloantiserum. Similarly, there was no graft rejection following the injection of anti-donor alloantiserum and complement. These results show that cultured islet allografts are not susceptible to antibody and complement.

Two signals are required for T cell activation, and because of this transplantation antigen, of itself, is not the major barrier to grafting. The major stimulus for the rejection response come from active antigen presentation by donor APC's. It is possible to reduce allograft immunogenicity by removal of these cells from the graft prior to transplantation. This procedure has been shown to be effective in the case of thyroid, parathyroid, and islet cell transplantation in animals and in the case of parathyroid grafting in man. The cultured graft is in a metastable state in the immediate post-transplantation phase; such grafts are rejected by either active or passive immunization of the host animal. With the passage of time the metastable graft moves into a stable relationship with the host. This change is the result of tolerance induction in the adult animal. The fact that allografting can be carried out without a requirement for recipient immunosuppression suggests that the helper pathway involving processing of graft antigen and presentation on host APC's, is relatively inefficient in vivo. Experimentally, lymphokine provided by T cell triggering in the region of the metastable graft does not lead to the generation of systemic immunity, suggesting that there are much more stringent requirements for the expression of T helper function in vivo than in vitro.

The survival time of mouse thyroid, transplanted under the kidney capsule of an H-2 incompatible recipient, is extended by holding the thyroid in organ culture for 12 days prior to transplantation.

Menopausal flushing can be considered as an intermittent loss of peripheral vasomotor control. Thermal entrainment testing has been used to assess the degree of peripheral vasomotor control in a preliminary study of seven women receiving oestrogen replacement therapy in the form of percutaneous cream. Significant improvement was demonstrated in the degree of control over a 3-month period in those patients who were symptomatically improved. We suggest that oestrogen exerts an influence on peripheral vasomotor control and flushes and sweats occur when this influence is removed.

Spontaneous diabetes in NOD mice has an immunologically mediated cause and is a T cell-dependent process. When diabetic NOD mice are grafted with cultured BALB/c islet tissue, the islet graft is destroyed by disease recurrence in the graft. Disease recurrence is a CD4 T cell-dependent process as determined by in vivo administration of anti-CD4 or anti-CD8 monoclonal antibody prior to the grafting of islet tissue. Cyclosporine functions in the early sequence of T cell activation by regulating the production of messenger RNA for lymphokines synthesis. Cyclosporine does not inhibit the synthesis of lymphokine once the lymphokine message is present in the cell. Thus, we might expect cyclosporine to be relatively inefficient as an agent for the regulation of disease recurrence following transplantation to actively diabetic recipients, and we would expect cyclosporine to be more effective when administered before the onset of the disease. Low-dose cyclosporine treatment can prevent development of the disease when the drug is administered before the onset of disease. Data presented here show that cyclosporine is ineffective in controlling disease recurrence in the islet graft transplanted to actively diabetic animals. Also, when we eliminate CD4 T cells from the diseased animals and graft islet tissue prior to the administration of cyclosporine, we are unable to maintain a graft with low-dose cyclosporine therapy. This result leads us to conclude that, although anti-CD4 treatment controls the expression of the disease process and allows the survival and function of the islet graft, this treatment does not return diseased animals to the prediabetic condition in which the development of diabetes can be controlled by low-dose cyclosporine therapy.

Normal lymphocyte transfer reactions have been used to test the alloreactivity of lymphocytes which have migrated through lymph nodes (i.e., in efferent lymph) or nonlymphoid tissues (i.e., in afferent lymph) in sheep. Lymphocytes from afferent lymph are much less efficient at inducing a normal lymphocyte transfer lesion than lymphocytes from efferent lymph. Afferent cell preparations (which contain about 10% macrophages) do, however, cause a greater inflammatory response in the early part of the reaction, but this is at least partly nonspecific. A mixture of afferent and efferent cells produces a lesion which is simply the sum of the two expected reactions, suggesting that the afferent lymphocytes are not merely inhibited by a factor or cell in the preparation.

The survival of thyroid allografts in mice was prolonged by either holding the grafts in vitro culture for 20 to 27 days or by cobalt-60 irradiation of the donor 2 days before transplantation with or without the intravenous injection of colloidal carbon just before removing the thyroid from the donor. In both cases the rejection process was restored by an intravenous injection of recipients with living peritoneal exudate cells (50 to 80 percent macrophages) syngeneic to the thyroid donor.

Culture of mouse pancreatic islets in an oxygen-rich atmosphere before transplantation facilitates long-term allograft survival without the use of immunosuppression. A comparison of the capacity of ultraviolet (UV) irradiated and live spleen cells of donor origin to induce allograft rejection showed that UV-irradiated spleen cells were not immunogenic; live spleen cells were immunogenic and their injection triggered allograft rejection. Following treatment with irradiated spleen cells from about day 30 post-transplantation, recipient animals were able to withstand subsequent challenges with 10(6) and 10(7) viable donor spleen cells. Untreated animals rejected their graft when challenged with 10(6) donor spleen cells. That is, treatment with UV-irradiated cells stabilized the islet allograft by inducing a state of tolerance. Subsequent transplantation of stabilized animals with uncultured thyroids of both donor origin and from a third party strain demonstrated that the tolerance was specific. In vitro test of immune reactivity showed this tolerance was not due to the deletion of antigen reactive cells.