The diagnosis of renal allograft rejection: an improved assessment of graft infiltration using image analysis

These results show that image analysis is an accurate alternative to point counting in the assessment of infiltration in renal allograft biopsies and can provide an efficient and rapid diagnosis of cellular rejection in the transplanted patient.

Biochemically detected HLA-DQ polymorphism in DR-matched donors and recipients of renal allografts

We performed a retrospective biochemical analysis of HLA-D-region antigens of serologically DR-compatible donors and recipients of renal allografts. No incompatible D-region antigens were detected in grafts with a stable clinical course--i.e., there were no rejection episodes--whereas incompatibility for one or more D-region antigens was found in all 13 grafts with rejection. Thus, mismatched D-region antigens may provide a stimulus for early rejection in these grafts.

Transfusion induces blood donor-specific suppressor cells

Transfusion with blood from the organ donor before transplantation can prolong the survival of renal allografts in the rat. To determine if the beneficial effect of preoperative blood transfusion was due to the generation of donor-specific suppressor cells, in vivo and in vitro adoptive transfer experiments were performed. Lymphoid cells were harvested from transfused and untreated rats. These cells were then either (1) transferred to lightly irradiated (200 R) syngeneic hosts which were subsequently challenged with a kidney allograft (in vivo assay) or (2) titrated as regulator cells into naive unidirectional MLC such that the regulator and responder populations were syngeneic. In the LEW-RT1 to DA-RT1av1 strain combination, the adoptive transfer of thoracic duct lymph (TDL) or lymph node (LN) cells (5 x 10(7) to 7.5 x 10(7) cells) from DA animals transfused with LEW blood, 7 days previously into syngeneic (DA), lightly irradiated (200 R) hosts resulted in the indefinite survival of LEW kidney allografts. The phenomenon was blood donor-specific and dose-dependent. In contrast the adoptive transfer of spleen cells (10(7) to 10(8] from blood transfused hosts 7 days after transfusion had no effect on renal allograft survival. In vitro the addition of LN or TDL regulator cells, harvested from DA rats transfused with LEW blood, to a unidirectional MLC (DA responders, LEW stimulators) resulted in a significant depression of the proliferative response when compared with the proliferation of these same cells without the addition of these regulator cells or with the addition of LN or TDL regulator cells from a DA rat transfused with third party (PVG-RT1c) blood. The depression of the proliferative response observed in vitro, was blood donor specific. When LN or TDL regulator cells from a DA rat transfused with PVG-RT1c blood were added to a unidirectional MLC between DA responders and PVG stimulators, a significant depression in the proliferative response was observed. These in vitro findings were confirmed in two other strain combinations (LEW-PVG, and DA-PVG). Thus a single blood transfusion results in the induction of donor-specific suppressor cells detectable both in vivo and in vitro 7 days after transfusion in some but not all lymphoid compartments.

Transfusion induces blood donor-specific suppressor cells

Transfusion with blood from the organ donor before transplantation can prolong the survival of renal allografts in the rat. To determine if the beneficial effect of preoperative blood transfusion was due to the generation of donor-specific suppressor cells, in vivo and in vitro adoptive transfer experiments were performed. Lymphoid cells were harvested from transfused and untreated rats. These cells were then either (1) transferred to lightly irradiated (200 R) syngeneic hosts which were subsequently challenged with a kidney allograft (in vivo assay) or (2) titrated as regulator cells into naive unidirectional MLC such that the regulator and responder populations were syngeneic. In the LEW-RT1 to DA-RT1av1 strain combination, the adoptive transfer of thoracic duct lymph (TDL) or lymph node (LN) cells (5 x 10(7) to 7.5 x 10(7) cells) from DA animals transfused with LEW blood, 7 days previously into syngeneic (DA), lightly irradiated (200 R) hosts resulted in the indefinite survival of LEW kidney allografts. The phenomenon was blood donor-specific and dose-dependent. In contrast the adoptive transfer of spleen cells (10(7) to 10(8] from blood transfused hosts 7 days after transfusion had no effect on renal allograft survival. In vitro the addition of LN or TDL regulator cells, harvested from DA rats transfused with LEW blood, to a unidirectional MLC (DA responders, LEW stimulators) resulted in a significant depression of the proliferative response when compared with the proliferation of these same cells without the addition of these regulator cells or with the addition of LN or TDL regulator cells from a DA rat transfused with third party (PVG-RT1c) blood. The depression of the proliferative response observed in vitro, was blood donor specific. When LN or TDL regulator cells from a DA rat transfused with PVG-RT1c blood were added to a unidirectional MLC between DA responders and PVG stimulators, a significant depression in the proliferative response was observed. These in vitro findings were confirmed in two other strain combinations (LEW-PVG, and DA-PVG). Thus a single blood transfusion results in the induction of donor-specific suppressor cells detectable both in vivo and in vitro 7 days after transfusion in some but not all lymphoid compartments.

Pancreatic islet transplantation

Successful transplantation of the endocrine pancreas in Type I diabetes with complete correction of the glucose metabolic abnormalities may prevent progression or development of the microangiopathic complications of the disease. This could be achieved by transplantation of the whole pancreas as a vascularized graft (the only available clinical approach at present), transplantation of isolated islets or of fetal pancreas. Since transplantation of the pancreas as a vascularized graft is associated with a significant peri-operative morbidity and requires immunosuppression to prevent rejection it is unlikely to be applicable at a relatively early stage of the disease, before microangiopathic complications become irreversible. For this reason transplantation of pancreatic islets or fetal pancreas is the only approach likely to be acceptable. Transplantation of isolated islets in the rodent does correct experimental diabetes, but recurrence of disease is seen in the spontaneous diabetes of the Biobreeding (BB) rat and the non-obese diabetic (NOD) mouse. Furthermore suppression of rejection of allogenic islets has proved difficult. In large mammals, including man, the lack of a technique to prepare isolated islets in a relatively pure form has been a further obstacle to development. Recently this problem has been overcome, allowing separation of islets in relatively large numbers with adequate purity, bringing closer the time when clinical trials might be considered. However, rejection and disease recurrence are likely to remain major obstacles, although experimental work suggests that both can be overcome.

Protease activity in pancreatic islet isolation by enzymatic digestion

Commercial Collagenase* prepared from Clostridium histolyticum is widely used in isolation of pancreatic islets. It is known that the enzyme is very impure and that there are substantial variations in effectiveness between batches. Our studies suggest that one of the impurities of importance in islet isolation is a protease that has not been very well characterized. Comparison of two batches of enzyme, one of which was known to give good yields of islets and the other poor yields, showed that they had very similar activity against collagen (measured by digestion of insoluble collagen followed by assay of soluble products with ninhydrin) but substantially different activities against azocasein as measured by optical density increase (measured by release of dye). Eighteen batches of Collagenase were examined for efficiency in islet isolation, and the yields obtained correlated with manufacturer's data of activity against casein. The data show that low caseinase activity is associated with performance in islet isolation (r = .5 after adjusting for collagenase activity). The effect of supplementing a batch of collagenase, known to be poor in isolating islets, with proteolytic enzymes was investigated. Trypsin and papain had apparently no effect, but dispase significantly increased yield. Dispase alone failed to digest pancreas. Size-exclusion high-performance liquid chromatography identified a peak associated with high protease activity and efficiency in islet isolation, having an Mr of approximately 30,000, compared to 78,000 for collagenase. The protease, like collagenase, is inhibited by EDTA. Increased Ca2+ and Mg2+ (up to 10 mM) did not affect activity. Both the protease and collagenase are stable under normal use but are inactivated by heating at 56 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Hyperparathyroidism, hypertension and loop diuretic medication in renal transplant recipients

The associations between serum parathyroid hormone (PTH), blood pressure and hypotensive medication were analysed in 282 renal transplant recipients. Among patients with a normal concentration of serum creatinine there was no correlation between serum PTH and blood pressure but in those receiving hypotensive medication serum PTH was appropriately twofold greater than in those not taking hypotensive medication. Analysis revealed that the dominant contribution to this association was a specific association with loop diuretic therapy. When all patients were stratified according to creatinine clearance, serum PTH was always greater in patients receiving loop diuretics but this difference was particularly striking in the patients with the poorest graft function. It is postulated that loop diuretics exacerbate the hyperparathyroidism which complicates renal disease.

Separation of pancreatic islets by fluorescence-activated sorting

To allow clinical pancreatic islet transplantation, the yield and purity of islets must be improved. Intravital staining of islets with neutral red is a specific, nontoxic technique for labeling islets of various species. Using neutral red-stained rat islets, we investigated the known fluorescence absorbance and emission spectra in comparison with unstained exocrine tissue and have shown that stimulation with light of wavelength between 500 and 560 nm produces detectable emission greater than 610 nm, which is absent from unstained exocrine tissue. The PARTEC cell sorter is an inexpensive alternative to currently available fluorescence-activated cell sorters and has a sorting mechanism based on a piezoelectric valve. We made extensive modifications to this machine to allow passage of particles up to 300 micron diam. Using rat pancreas stained intravitally with neutral red and dispersed by intraductal collagenase technique, we have shown that islets can be accurately identified in a high-speed flow system and sorted to a purity of greater than 90% islet tissue. The islets remain intact and viable as determined by supravital staining and isogeneic transplantation to the kidney capsule site. These studies prove the feasibility of separating intact islets by fluorescence-activated sorting.

Metabolic function of intraportal and intrasplenic islet autografts in cynomolgus monkeys

Intraportal islet autografting can restore near-normal glucose homeostasis in large diabetic animals, but the long-term failure rate of such grafts remains high. To assess the effect of the site of transplantation, we compared the hormonal responses to glucose (500 mg/kg i.v.) of intraportal (IP) and intrasplenic (IS) islet autografts in the cynomolgus monkey previously rendered diabetic by total pancreatectomy. Intravenous glucose tolerance tests (IVGTTs) 6 wk after IP grafting (n = 10) demonstrated nearly normal plasma glucose changes, with qualitatively normal but quantitatively reduced insulin and glucagon responses; only two animals have maintained these responses for greater than 2 yr. IVGTTs 6 wk after IS grafting (n = 4) demonstrated more abnormal plasma glucose changes, with qualitatively normal but weak insulin responses and glucagon levels that did not fall in response to hyperglycemia; only one animal has maintained fasting normoglycemia for greater than 9 mo. These results suggest that IS transplantation confers no benefit over IP transplantation in this model.

Normalization of hyperglycemia in diabetic rats by intraportal transplantation of cryopreserved islets from four donors

Techniques for freezing rat islets have been examined by the intensive use of the supravital stains fluorescein diacetate and ethidium bromide. By the use of a simple scoring system, the effect of the cooling rate, treatment with dimethyl sulfoxide (DMSO), rate of thawing, and postthaw culture were examined. These studies showed the most effective method to be a 24-h culture of islets, followed by partial incubation with 20% DMSO at 0 degrees C, followed by seeding at -8 degrees C in an alcohol bath. The islets were then cooled at a rate of -0.25 degrees C/min to -40 degrees C followed by quenching in liquid nitrogen at -196 degrees C. Rapid thawing at 37 degrees C was then followed by a 24-h culture. Islets from four Lewis rat donors were cryopreserved, counted, and transplanted intraportally into streptozocin-induced diabetic Lewis rats. Corresponding control transplants were performed with islets from four donors only cultured for 48 h. The results showed that reversal of hyperglycemia in severely diabetic rats was obtained at 5, 5, 6, 6, 6, or 8 days with cryopreserved islets from four donors, compared to reversal of diabetes at 1, 4, 5, 6, 7, and 12 days with islets from four donors subjected to culture alone. The new cryopreservation technique has several small modifications over previously described methods and results in a significant improvement in islet survival.

Exocrine contamination impairs implantation of pancreatic islets transplanted beneath the kidney capsule

The effect of exocrine contamination on islets implanted under the kidney capsule has been studied by histological examination of pure or exocrine-contamination human, monkey, or rat islets transplanted to the kidney capsule of the nude rat, monkey, or rat, respectively. Exocrine contamination resulted in an appearance suggestive of impaired islet implantation, due to tissue necrosis and subsequent fibrosis. The effect of exocrine contamination was examined quantitatively in a rat islet isograft model in which handpicked DA rat islets were transplanted under the kidney capsule of normal DA rats. The islets were either pure or deliberately recontaminated with exocrine tissue (50 or 90% contamination). Four hundred pure islets were placed under one kidney capsule and 400 islets (of similar size and from the same islet preparation) were contaminated and then placed under the contralateral kidney capsule. After 2 weeks the kidneys were removed and extracted for insulin content. The insulin content of kidneys bearing islets contaminated by either 50 or 90% exocrine tissue was significantly reduced when compared to the contralateral kidney bearing pure islets. These findings support the view that exocrine contamination of islets resulted in impaired islet implantation when transplanted to a confined site such as the kidney subcapsule.

Genomic analysis identifies class II mismatches in serologically DR-compatible human renal allografts

Many studies, including those from our own center, have shown that matching the donor and recipient for HLA-DR antigens has a beneficial effect on the outcome of cadaveric renal transplantation. However, cases of irreversible graft rejection are sometimes seen in patients who have received an HLA-DR-compatible kidney, suggesting that serologic compatibility for HLA-DR may not always ensure reduced alloreactivity toward the graft. We have examined a number of recipients and their serologically DR-compatible cadaveric donors by Southern blotting and hybridization with locus specific HLA class II probes in order to determine whether in these patients there were class II mismatches that had been undetected by serology. The results show that the analysis of DR beta restriction fragment patterns does little more than complement and confirm the serologic identification of HLA-DR. Hybridization with DQ alpha and DQ beta probes, however, significantly extends the number of DQ specificities that can be detected and suggests that DQ mismatches in DR-compatible donor-recipient pairs may be more common than previously supposed, although it is not possible to draw any conclusions on the influence of DQ incompatibilities in the presence of DR compatibility on graft outcome.

Renal transplantation in patients over 55 years old

From 1975 to 1987, 507 patients, of whom 63 (12.4 per cent) were over 55 years old at the time of operation, received first cadaver renal transplants. The annual percentage of recipients given transplants after the age of 55 has risen from 0 per cent in 1975 to 44 per cent in 1987. Of the 63 older patients, 41 had at least one serious non-renal disease at the time of transplantation. Perioperative mortality rate was 3 per cent. After successful transplantation these patients remained subject to a significant number of serious complications, even in the cyclosporin era. Despite these adverse factors, actuarial graft survival for the population over 55 years of age was no worse than for those patients receiving first cadaver grafts who were under 55 years old, although patient survival was poorer in the former group (P = 0.027). Analysis of the subgroup of 56 patients treated with an immunosuppression protocol containing cyclosporin failed to show any adverse effect of age on either graft or patient survival. It is concluded that renal transplantation can be as successful in patients over 55 years of age as it is in younger patients and, given an adequate supply of kidneys, should be considered the treatment of choice for the elderly patient with end-stage renal failure.

Genetic aspects of the blood transfusion effect

The genetic requirements for the induction of the blood transfusion effect have been investigated in a genetically well-defined model. The survival of fully vascularized, heterotopic murine cardiac allografts was measured after a single preoperative transfusion of blood from mice selected to share MHC and/or minor histocompatibility (miH) antigens with the organ donor. The effect of a transfusion from a donor unrelated to the heart donor (third-party transfusion) on allograft survival was also determined. Five strain combinations were used for these experiments. The results obtained illustrate a number of important aspects of the blood transfusion effect in this model: (1) Donor-specific blood transfusion, where MHC and miH were shared by the blood donor and the organ donor, always induced prolonged graft survival. (2) The sharing of the whole MHC (H-2) by the blood donor and organ donor was found to be sufficient to prolong allograft survival in the five fully allogeneic strain combinations tested. (3) The sharing of miH antigens only was not sufficient to induce prolonged cardiac allograft survival. Special cases were identified showing that several factors could interact to potentiate the action of miH antigens in the induction of the blood transfusion effect. (4) Transfusion with blood from a third-party donor was effective in some strain combinations. In one recipient, blood from several third-party strains of mice, sharing neither MHC nor miH antigens with the organ donor, induced prolonged graft survival. We suggest that the mechanism by which third-party blood has a beneficial effect on graft survival is through crossreaction(s) between the blood donor and the organ donor. The results obtained in this study fit very well with one model for the cellular mechanism by which the transfusion effect may be mediated. This may be the means by which blood from randomly selected donors has a beneficial effect on graft survival in clinical transplantation.