ANALYSIS OF MECHANISM OF IMMUNOSUPPRESSIVE DRUGS IN RENAL HOMOTRANSPLANTATION

The role of afferent lymphatics in the rejection of skin homografts

Experiments have been carried out on guinea pigs of two isogenic strains to elucidate the role of afferent lymphatic vessels in the rejection of orthotopic skin homografts. Graft beds were prepared in partially isolated skin flaps with an intact sustaining vascular "umbilical cord" in which a lymphatic connection with the host could be retained or abolished at will. In the absence of demonstrable lymphatic connections between flap and host, intra-flap homografts long outlived similar grafts transplanted to conventional sites in intact skin and, rather than being specifically rejected, died as a consequence of ischemic necrosis of the flap. When lymphatic drainage was retained, intra-flap homografts were rejected in the usual manner. Hosts of long-term intra-flap homografts did not develop sensitivity, as evidenced by the "first set" type rejection of subsequent test grafts, or by the long-term survival of a second skin graft transplanted to a new flap raised on the opposite side of the host's body. Intra-flap skin homografts were rejected if (a) the hosts had been presensitized, (b) they were grafted concomitantly with a skin homograft placed in a conventional site, or inoculated with a suspension of donor lymphoid cells, or (c) if the lymphatic drainage was restored by reimplantation of the hitherto partially isolated flap to an appropriate vascular bed. These findings and others indicate that an intact lymphatic drainage in its bed is essential for an orthotopic skin homograft to sensitize its host. Various experiments were carried out in which intra-flap homografts were used as "indicators" for the acquisition of specific active or adoptive immunity by their hosts. By transplanting skin homografts to conventional beds concomitantly with intra-flap grafts and then excising the former at various intervals, it has been found that a graft must be in residence for a minimum period of 4 days to evoke the development of a detectable level of sensitivity in the host. Furthermore, by replacing either freshly prepared or long-term skin flaps bearing skin homografts in vascular beds on the trunk and determining the subsequent survival times of the homografts, evidence has been obtained suggesting that reestablishment of a functional lymphatic system in a free skin graft may take as long as 9 days. Using intra-flap homografts as indicators of adoptive immunization of the host, we found that as few as 50 x 10(6) isologous peripheral blood leukocytes from a specifically sensitized animal will transfer an effective level of sensitivity. We also found that hyperimmune serum, in relatively large amount, exerts a weak but definite adverse effect upon either freshly or recently transplanted intra-flap grafts.

The present position and future prospects of organ transplantation

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The management, function and histology of long functioning renal allografts in dogs on immunosuppressive drug therapy

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Renal homotransplantation in rats. II. Tolerant recipients

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Renal homotransplantation in rats. I. Allogeneic recipients

Within 3-6 hr after the reestablishment of the circulation, a characteristic pathology developed in renal homotransplants. Blood monocytes and lymphocytes adhered to large thin-walled vessels of the septa carrying interlobular arteries, traversed their walls, and aggregated in the connective tissue spaces around them. Within 3 days, the number and size of the extravascular cells markedly increased, filling the septa completely and spreading from them centrifugally to occupy the intertubular spaces throughout the cortex. The composition of these aggregates at first was a mixture of lymphocytes and monocytes, and later consisted of large blast cells, macrophages, a few plasma cells, and polymorphonuclear leukocytes. Mitotic activity was seen 2 days after surgery among the large blast cells and increased to a maximal level a day later. Coevally with these changes, the thin-walled septal vessels, intertubular veins and capillaries, and finally, arteries and arterioles, in that order, were damaged. Focal injury of tubules was slight 24 hr after homografting; widespread cortical necrosis had developed 5-7 days later. At no time up to 7 days were concentrations of immunoglobulins detected by fluorescence microscopy in the transplanted kidneys. The morphologic manifestations and temporal sequences of renal homograft destruction suggested that several mechanisms acted synergistically to eliminate the transplant. The initial injury appeared to be the result of an interaction between host lymphoid cells and target endothelium, a phenomenon akin to allogeneic inhibition; followed by spreading ischemia; additional contact injury to tubules; and nonspecific inflammation associated with necrobiotic tissue.

Drug-induced tolerance for skin allografts across the H-2 barrier in adult mice

Mice treated with methylhydrazine derivatives for 3 to 4 weeks before the transplantation showed markedly prolonged survival times for allogeneic skin grafts differing at the H-2 histocompatibility locus. Presumably permanent tolerance was induced in about 20 to 30 percent of the mice when the drug treatment was combined with a single injection of additional donor antigen. The tolerance persists without further drug treatment and is specific for donor tissue.

A theory of the action of cancer chemotherapeutic drugs

This paper presents an analysis of the results of cancer therapy, based on the histories of treated and untreated cancers taking into account the biology of immunity and drug action.

Cancer chemotherapeutic drugs in addition to a direct action on the malignant cells, act on the host's immune system. The importance of tumour–host interactions in determining the overall progress of the tumour is emphasized.

It is postulated that in the early stages of therapy, remission occurs because the drug is given at a time when the host has either some degree of immunity against the tumour, or has a reversible immune tolerance with respect to the tumour antigen. In contrast, in the later stages of treatment, immunity against the tumour is depressed and this is a major cause of therapeutic failure.

Humoral Antibodies in Patients After Renal Homotransplantation

Humoral antibodies have been demonstrated by antiglobulin consumption tests to be present in the serum of virtually all patients after renal homotransplantation. The most completely characterized was a γG immunoglobulin distinct from the Forssman antibody which reacts against sheep but not against human red cell antigens, and which absorbs selectively against panels of human liver, kidney or white blood cells. This antibody appeared within a few days or weeks after transplantation, usually shortly after a rejection episode, and was more or less continuously detectable thereafter. The antibody was found in all of 10 patients studied during the first 4 post-transplant months, and in 13 of 14 patients tested from 4 months to more than 2 years after operation. Preliminary observations are included on another humoral antibody which does not react with sheep RBC stromata, but which can also be measured with a modified antiglobulin consumption test. The latter antibody was less commonly demonstrable, but it also exhibited specific absorption characteristics when tested against a panel of leukocytes obtained from volunteers. The implications of these findings are discussed in relation to the possible value of such sera for histocompatibility typing, as well as the possible role of such antibodies in promoting homograft enhancement.

Comparative results of cadaver and related donor renal homografts in man, and immunologic implications of the outcome of second and paired transplants

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Experimental and clinical observations after homotransplantation of the whole liver

During the past 10 years, much has been learned about homotransplantation of the whole liver using either a replacement (orthotopic) homograft or an auxiliary organ which is inserted at an ectopic site without removal of the recipient’s own liver. The available information concerning these operations has been reviewed from animal experiments, and from the handful of attempts at clinical application.