Percutaneous transluminal angioplasty. The procedure of choice in the hypertensive renal allograft recipient with renal artery stenosis

A retrospective review of 547 renal transplants performed over a six-year period revealed allograft renovascular hypertension secondary to RTAS in 39 (7.1%) patients. Percutaneous transluminal angioplasty (PTA) resulted in immediate cure or improvement in 76% of the patients, increasing to 83% in patients with functioning kidneys at a mean follow-up period of 30 months (1-72 months). The renal artery stenosis (RTAS) was equally distributed between living-related and cadaver kidney recipients and did not appear to be more prevalent in end-to-end or end-to-side anastomoses. The blood pressures fell from pre-PTA levels of 167 +/- 22 mmHg systolic to 141 +/- 23.7 post-PTA and 102 +/- 11 mmHg diastolic pre-PTA to 88 +/- 12 mmHg post-PTA (P less than 0.01). Of 25 cured or improved patients, 24 are on significantly less hypertensive medication. Two patients died of causes unrelated to the PTA and only one patient lost a kidney because of the procedure. Compared with operation, PTA is a safer and more effective procedure for the initial treatment of RTAS.

Transplantation of cultured pancreatic islets to BB rats

Pancreatic islets held in tissue culture before transplantation into artificially induced diabetics are not rejected. In animals and human identical twin transplants, the autoimmunity of naturally occurring diabetes may destroy islets, even if rejection is avoided. Therefore we studied whether autoimmune damage of islets can be avoided by pretransplant culture. Recipients were BB rats, which spontaneously developed diabetes. Donors were either Wistar Furth (WF) (major histocompatibility [MHC] identical to BB rats) or Lewis (MHC nonidentical to BB rats). Islets were inoculated into the portal vein either immediately after isolation or after 14 days in tissue culture (95% air, 5% CO2, 24 degrees C). Recipients of cultured islets received a single injection of 1 ml of antilymphocyte serum at the time of transplant. Recurrence of diabetes after transplantation of freshly isolated MHC incompatible Lewis islets occurred rapidly on the basis of rejection or autoimmune damage (or both). Precultured Lewis islets had prolonged or permanent survival. Freshly isolated MHC compatible WF islets were destroyed, and no improvement was seen with culture. We conclude that autoimmune destruction of transplanted islets can be avoided by tissue culture, as can rejection. This is important because this strategy is effective only if recipient and donor differ at the MHC locus. Islet donors may need to be selected on the basis of disparity of histocompatibility factors.

Immunologic studies of the prediabetic stage in the spontaneous autoimmune diabetes mellitus of the BB rat

Twenty-eight BB diabetes-prone rats underwent prospective analysis to determine levels of circulating Ia antigen-bearing "activated" T lymphocytes prior to 50 days of age using mouse antirat monoclonal antibodies OX6 (anti-Ia) and W3/13 (anti-T-cell) and a fluorescence-activated cell sorter. Pancreatic biopsies were obtained within 48 hrs of lymphocyte sampling and histologically examined for the presence of a lymphocytic infiltrate. Elevated levels of "activated" T lymphocytes (above 4.00%) accurately identified a prediabetic stage and predicted which BB rats would subsequently become diabetic (93% sensitivity). The insulitis lesion occurs in the latter portion of this immunologically defined prediabetic stage just prior to the development of hyperglycemia. This observation suggests that islet cell destruction represents the final focus of a chronic immune response.

The influence of T-lymphocyte precursor cells and thymus grafts on the cellular immunodeficiencies of the BB rat

To determine whether abnormal T-lymphocyte precursor cells or an abnormal thymus is responsible for the immunologic deficiencies of spontaneously diabetic BB rats, thymus grafts or T-cell-depleted bone marrow cells were exchanged between diabetes-prone and non-diabetes-prone animals. Analysis of peripheral lymphocyte populations from these recipients with monoclonal antibodies, a fluorescence activated cell sorter, and mixed lymphocyte culture tests indicate that an abnormal thymus is not responsible for the immunodeficiency of BB rats, but that the defect resides within the lymphocyte precursor pool.

"Activated" T-lymphocyte levels in the spontaneously diabetic BB rat syndrome

About 50% of individual members of a diabetes-prone stock of BB rats eventually become hyperglycemic (usually between 60 and 180 days of age) while the remainder remain normoglycemic for life. Circulating levels of Ia antigen bearing T-lymphocytes from different lymphoid compartments of acutely diabetic and normoglycemic (but diabetes prone) BB rats were determined with monoclonal antibodies in an effort to analyze the temporal relationship between levels of this unusual T cell antigen and the onset of diabetes. In young normoglycemic rats elevated blood levels of Ia-positive T-lymphocytes (greater than or equal to 4.00%) predicted the future development of hyperglycemia with a sensitivity of 85% and a specificity of 83%. The interval between the identification of these elevated levels and the onset of diabetes ranged from 22 to 82 days. After the development of hyperglycemia the level of Ia-positive T-lymphocytes declined progressively in all lymphoid compartments with chronicity of the diabetes. We conclude that Ia antigens bearing T cells serve as immunologic "markers" of susceptibility to diabetes in this "high-risk" population and probably reflect an ongoing immune process during the prediabetic state. Similar findings in humans with a family history of diabetes might lead to identification of prediabetic individuals and allow selective use of immunomodulation to prevent the disease.

Treatment of lymphocele in renal allograft recipients

Retroperitoneal lymphoceles developed in 12 renal allograft recipients during the last nine years. The interval between transplantation and the development of symptoms averaged seven months. The specific syndrome suggesting the presence of a lymphocele included lower abdominal swelling, weight gain, and, occasionally, fever without an obvious source of infection. Although these symptoms mimicked allograft rejection, diagnosis was easily made by ultrasound and intravenous pyelogram. Surgical marsupialization of the lymphocele with drainage into the peritoneal cavity proved to be an effective treatment.

Increased incidence of Ia antigen-bearing T lymphocytes in the spontaneously diabetic BB rat

The frequency of Ia-positive T lymphocytes in spontaneously diabetic BB rats was assessed by using monoclonal antibodies and a fluorescence-activated cell sorter. These cells peaked in frequency during the early stages of hyperglycemia, with a gradual decline toward normal as the disease progressed. Significantly increased numbers of Ia-positive T cells were detected in both helper (W3/25+) and cytotoxic-suppressor (OX8+) subsets. The elevated levels of Ia-positive T lymphocytes in these rats may be relevant to the immune destruction of their beta cells.

Increased incidence of Ia antigen-bearing T lymphocytes in the spontaneously diabetic BB rat

The frequency of Ia-positive T lymphocytes in spontaneously diabetic BB rats was assessed by using monoclonal antibodies and a fluorescence-activated cell sorter. These cells peaked in frequency during the early stages of hyperglycemia, with a gradual decline toward normal as the disease progressed. Significantly increased numbers of Ia-positive T cells were detected in both helper (W3/25+) and cytotoxic-suppressor (OX8+) subsets. The elevated levels of Ia-positive T lymphocytes in these rats may be relevant to the immune destruction of their beta cells.

The importance of immunologic factors in the pathogenesis of encephalomyocarditis virus induced diabetes in mice

The pathogenesis of EMC virus induced diabetes has generally been thought to be caused by direct cytopathic effect of the virus on beta cells with susceptibility or resistance dictated primarily by the density of viral receptors on the beta cells of different individuals. The histological finding of insulitis, our demonstration of a protective effect of immunosuppression with ALS or anti-theta antibody and silica supports host immune factors as important determinants of susceptibility. A critical role of the immune system might be mediated by autoimmune destruction of EMC-virus infected beta cells. In susceptible strain mice treated with low dose cyclophosphamide to deplete suppressor cells, which may halt the autoimmune process and allow recovery, a prolonged period of hyperglycemia was demonstrated as compared to controls. Bone marrow exchanged between susceptible and resistant strains was also found to alter susceptibility. "B mice", deficient in T lymphocytes, when infected with EMC virus had a decreased incidence of diabetes. Susceptibility to EMC diabetes may be dictated by the autoaggressive response of host immune system to beta cells altered by EMC virus infection.

Increase of basal cell membrane area of the retinal pigment epithelium in experimental diabetes

Stereological analysis of electron micrographs of the pigment epithelium of rats with drug-induced diabetes demonstrated an increase of plasma membrane surface area at the basal aspect of the cells. In none of the diabetic animals examined was there any evidence of breakdown of the blood-retinal barrier to the protein tracer, horseradish peroxidase. Statistically significant increases in basal plasma membrane length and surface density (surface area per unit cell volume) were measured in both streptozotocin and alloxan-injected rats after four weeks of diabetes. When hyperglycemia in streptozotocin-injected rats was promptly reversed by transplantation of normal pancreatic islets, the increase of membrane surface area did not occur. We conclude, therefore, that increased basal surface area of pigment epithelial cells is related to the diabetic condition rather than to a toxic action of the diabetogenic agents. Furthermore, increased membrane surface area was present in streptozotocin-diabetic rats killed after six months of diabetes indicating that the structural change is relatively stable. Relation of basal membrane alteration in the pigment epithelium to any functional disturbance of the barrier cell layer or of the retina in diabetes remains to be established.

Major histocompatibility complex restriction and transplantation immunity. A possible solution to the allograft problem

Studies of the survival of weakly histoincompatible skin grafts in which the Langerhans' cells (LC)5 have been replaced with major histocompatibility complex (MHC)-compatible or incompatible LC, as well as studies of the fate of cultured endocrine allografts in MHC-compatible and incompatible mice and rats, indicate that allografts are only recognized as foreign if they possess donor macrophages (or cells of this family), or if antigen presenting cells MHC-compatible with the graft can be provided by the host.

Influence of culturing on the functioning of major-histocompatibility-complex-compatible and incompatible islet grafts in diabetic mice

Culturing B10.BR (H-2k) islets promotes their survival in major histocompatibility complex (MHC)-incompatible BALB/c (H-2d) mice, but not in MHC-compatible CBA (H-2k) animals. These results provide further evidence that MHC restriction is involved in transplantation immunity--i.e., that allografts are only recognized as foreign if they possess donor macrophages (or cells of this family), or if antigen-presenting cells MHC-compatible with the graft can be provided by the host.

Numerical and functional abnormaLity of T suppressor cells in diabetic rats

Insulin-dependent diabetic patients have been reported to have abnormal suppressor T cell function. However, the importance of this abnormality in the etiology of the disease is difficult to evaluate, since the abnormality could be a result of hyperglycemia rather than a predisposing factor. A genetic condition in rats that closely resembles type I (insulin-dependent) diabetes mellitus made it possible to study their suppressor T cell status before they displayed the disease. Thus, monoclonal antibodies and a fluorescence-activated cell sorter were used to define lymphocyte subpopulations in these animals. In prediabetic rats the number of suppressor T cells was reduced strikingly. In vitro assays showed that lymphocytes from predisposed rats were also functionally deficient in regard to suppression. Susceptible rats inoculated with bone marrow cells from normal donors were protected from diabetes. Moreover, the numbers and functions of suppressor T cells in these marrow recipients were almost restored to normal. These observations indicate that a suppressor T cell abnormality is responsible for the hyperglycemia of diabetic rats and raises the possibility that the human disease has a similar etiology.

Influence of islet and bone marrow transplantation on the diabetes and immunodeficiency of BB rats

The results of islet transplantation in spontaneous autoimmune diabetes of BB rats were studied to determine whether this disease process might damage the transplanted islet tissue. Since BB rats are not genetically uniform, syngenetic grafts could not be used; therefore, allograft rejection was prevented by rendering BB rats immunologically tolerant of WF transplantation antigens by neonatal inoculation with bone marrow cells. Despite the resultant tolerant state, which permitted successful engraftment of WF skin allografts, the transplanted islets ameliorated the spontaneous diabetes of BB rats only briefly before they were destroyed by immune insulitis. BB rats from the diabetic stock were found to suffer from abnormalities in T lymphocytes and their subsets as well as defective immune response patterns. When analyzed with monoclonal antibodies specific for rat lymphocyte markers, BB rats of the diabetic stock were found to be lymphocytopenic. There was a reduction in helper T cells and a more severe deficit in the suppressor/cytotoxic subset. BB rats that were inoculated neonatally with bone marrow from normal donors were found to have a strikingly reduced incidence of diabetes. Moreover, the T cell functional, numerical, and microenvironmental defects that were present in noninoculated BB rats were restored in marrow-inoculated BB rats, findings possibly related to the decreased incidence of diabetes.

Analytical and functional studies on the T cells of untreated and immunologically tolerant diabetes-prone BB rats

Lymphocyte profiles of untreated diabetes-prone BB rats (BBDP) and their normal marrow-inoculated tolerant littermates were determined with the aid of a fluorescence-activated cell sorter by using monoclonal antibodies specific for rat T cell (W3/13) and T cell subsets (W3/25, T helper; OX8, T cytotoxic/suppressor). In contrast to non-diabetes-prone rats and to their marrow-inoculated littermates, untreated BBDP rats were found to be T lymphocytopenic with reduced W3/25+ cells and with a major loss of OX8+ cells. Moreover, their lymphocytes displayed depressed alloreactivity that was not restored by addition of exogenous IL 2.

Analytical and functional studies on the T cells of untreated and immunologically tolerant diabetes-prone BB rats

Lymphocyte profiles of untreated diabetes-prone BB rats (BBDP) and their normal marrow-inoculated tolerant littermates were determined with the aid of a fluorescence-activated cell sorter by using monoclonal antibodies specific for rat T cell (W3/13) and T cell subsets (W3/25, T helper; OX8, T cytotoxic/suppressor). In contrast to non-diabetes-prone rats and to their marrow-inoculated littermates, untreated BBDP rats were found to be T lymphocytopenic with reduced W3/25+ cells and with a major loss of OX8+ cells. Moreover, their lymphocytes displayed depressed alloreactivity that was not restored by addition of exogenous IL 2.

Effect of spontaneous diabetes on hormone release in BB/Phi rats: comparison between the isolated perfused pancreas/stomach/duodenum/spleen and the isolated perfused pancreas

We have studied the effects of spontaneous diabetes in BB/Phi rats on hormone release in response to amino acids (15 mM) and to amino acids (15 mM) plus glucose (10 mM) from isolated perfused pancreas/stomach/duodenum/spleen (PSDS) and from isolated perfused pancreas (P) preparations. In the PSDS preparation, diabetes reduced total integrated insulin output by 97% (from 1146 +/- 198 to 40 +/- 24 ng/65 min, P less than 0.001), and glucagon output by about 50% (from 51.6 +/- 13.1 to 24.0 +/- 3.7 ng/65 min, P less than 0.05), whereas somatostatin output did not change (105.5 +/- 48.1 to 110.1 +/- 36.9 ng/65 min). In the P preparation, integrated glucagon output fell by 91% (from 97.9 +/- 26.8 to 8.6 +/- 4.8 ng/65 min, P less than 0.01) whereas integrated somatostatin output more than doubled (from 28.1 +/- 7.5 to 69.6 +/- 14.2 ng/65 min, P less than 0.05). Intestinal glucagon and somatostatin contributions were estimated by comparing hormone release from the PSDS with that from the P preparations. We conclude that in our nondiabetic BB/Phi rats, the pancreas was the only source for the release of glucagon and that the intestinal tract secreted more somatostatin than the pancreas. In the diabetic BB/Phi rats, pancreatic glucagon and insulin release was virtually abolished while glucagon secretion from the intestinal tract increased and somatostatin secretion decreased.

Mycobacterial infections in renal allograft recipients

Primary mycobacterial infections developed in five of 565 patients who had transplants during a 15-year period. All had negative PPDs and normal chest roentgenograms; none had tuberculosis before transplantation. Atypical mycobacteria were cultured in three of five infections. All were treated with a multiple-drug regimen, including isoniazid, rifampin, ethambutol, and streptomycin sulfate. In four of five patients, there were serious drug-related complications. No major initial alteration of immunosuppressive therapy was necessary in any of the patients. During the study, a treatment policy was followed that included one year of isoniazid treatment of all recipients with a positive PPD, history of tuberculosis, chest x-ray film suggestive of tuberculosis, or PPD-positive donor. An additional 14 transplant recipients were treated in accordance with this policy without complications or subsequent mycobacterial infections (32-month average follow-up). Despite the low incidence of mycobacterial infection in this series, the potential lethality and morbidity mandate constant vigilance.

Influence of culturing on the survival of major histocompatibility complex-compatible and -incompatible thyroid grafts in rats

Culturing Fischer thyroid fragments promotes their survival in major histocompatibility complex (MHC) -incompatible ACI rats but not in MHC- compatible Lewis animals.

Percutaneous transluminal angioplasty treatment of renal transplant artery stenosis

Since June 1979, percutaneous transluminal angioplasty (PTA) has been the procedure of choice for renal transplant artery stenosis (RTAS) at the Hospital of the University of Pennsylvania. Of 241 renal allograft recipients, 17 (7%) when studied by arteriogram because of suspected RTAS proved to have significant stenosis (the mean reduction in luminal width for the group being 68%) and underwent PTA. RTAS was equally prevalent in cadaver and related kidney allografts and was no less common in HLA-identical related donor grafts, arguing against the importance of immune factors in etiology. RTAS was equally prevalent whether the anastomotic technique was end to end or end to side. However, when RTAS occurred after end to side anastomoses, it was usually postanastomotic. Fifteen of 17 of the attempts at dilation by PTA were successful by angiographic analysis. Thirteen of the 15 successfully dilated patients had long-term allograft survival and in all of these instances blood pressure (BP) was decreased after PTA. After a mean of 67 weeks, BP decreased from a systolic of 184 +/- 24 mm Hg pre-PTA to 135 +/- 15 mm Hg (P less than 0.001) and from a diastolic of 115 +/- 10 mm Hg pre-PTA to 87 +/- 11 mm Hg (P less than 0.001). The majority of patients continue to require antihypertensive drugs but in a less vigorous regimen than pre-PTA. Serum creatinine level fell following PTA from 1.9 +/- 0.6 to 1.7 +/- 0.5 mg/100 ml (P less than 0.01). Repeat angiographic study was done in nine patients, an average of 61 weeks after PTA, and no recurrent RTAS was identified. Three minor complications of PTA occurred but none led to long-term sequelae. Thus, we believe PTA of RTAS is relatively safe, carrying less mortality and morbidity than operative treatment, and is capable of improving BP control and renal allograft function.

Spontaneous diabetes in BB rats: evidence for a T cell dependent immune response defect

Approximately 50% of BB rats develop insulinopenic hyperglycaemia and ketosis spontaneously in association with insulitis. Amelioration of the syndrome by immunosuppression suggests a cell mediated immune pathogenesis. Analysis of the cell-mediated immune profile of overtly diabetic and normoglycaemic diabetes prone BB rats indicates that they are lymphocytopenic relative to non-diabetes prone BB rats and that the T cell pool is particularly affected. Furthermore, lymphocytes from diabetic and diabetes prone BB rats, while producing normal responses to the T cell mitogen concanavalin A, do not respond when mixed in vitro with major histocompatibility complex incompatible lymphocytes. This anergy is not restored either by enriching the responding cell population for T cells or by adding exogenous T cell growth promoting factor. Thus BB rats have a numerical and regulatory deficit of their T cells which could be related to their propensity for diabetes.

Invited commentary: an overview of pancreas transplantation--biologic aspects

The clinical results of vascularized pancreas transplants have improved somewhat during the last 5 years, the but technical problems of handling the pancreatic duct remain difficult. Clinical isolated islet allografts have rarely if ever succeeded. Rejection appears to be a more severe problem in pancreas or islet transplants than in other pancreas transplants. Nevertheless, if nonendocrine cells can be completely removed, transplanted beta-cells might have prolonged survival, since they probably lack Ia antigens that may be necessary to evoke an immune response. An additional biologic problem is the possible destruction (independent of rejection) of transplanted islet cells by autoimmune insulitis. This has been found to occur in spontaneously diabetic rats who received transplanted islets. Study of this animal model may provide important clues to the etiology and treatment or prevention of diabetes.