The histology at various stages of acute rejection in concordant xenogeneic heart transplantation. A sequential study in rodents

In an attempt to describe early morphologic changes in heterotopic xenogeneic heart transplantation a sequential study was performed in a hamster-to-rat model. Mild morphologic changes observed after four to six h were characterized by slight interstitial edema and focal myocyte damage with fragmentation and loss of myofibrillar elements. No lymphocytic infiltration appeared. Moderate morphologic changes observed after 12-24 h were characterized by moderate interstitial edema, and the appearance of mild hemorrhage and scattered extravasated neutrophilic granulocytes. The myocardium had more widespread areas with myocyte damage, sometimes with small foci of necrotic cells and adjacent neutrophilic granulocytes and macrophages. Vascular changes with perivascular edema and swelling of the endothelium were seen and a few neutrophilic granulocytes could be found in the vessel walls. No lymphocytic infiltration appeared. Severe morphologic changes observed after 44-48 h or at the time of complete rejection were characterized by severe interstitial hemorrhage, appearance of widespread necrosis and marked vascular changes with development of leukocytoclastic-like vasculitis, possibly with thrombosis. Only a few lymphocytes appeared. The findings were essentially different from those observed in allogeneic heart transplantations, where classical first-set allograft rejection was seen. In normal donor hearts and syngeneic transplanted hearts used as controls, no significant morphologic changes were demonstrated. On the basis of this study we consider xenogeneic acute rejection to be primarily of the humoral type.

Sequential, morphological, and antidonor antibody analysis in a hamster-to-rat heart transplantation model

The pathogenesis and the mechanism of accelerated graft rejection in concordant xenotransplantation are unclear. The histopathological features and kinetics neither fulfill the criteria of classic hyperacute rejection nor resemble an accelerated type of first-set allograft reaction. The aim of this study was to investigate the mechanism of concordant xenograft rejection in relation to the early morphological changes in hamster hearts transplanted to unmodified rat recipients by sequential, immunohistological analysis of grafts, regional lymph nodes, and spleens and to correlate these results to the production of antidonor antibodies, as determined by a flow cytometric assay. Histopathological features were characterized by a gradually increasing myocytolysis with fragmentation and loss of myofilaments. The first slight signs were observed a few hours after transplantation. Later, vascular changes developed, evolving into a leukocytoclastic type of vasculitis, eventually with thrombosis. No significant interstitial lymphocyte infiltration was present, but neutrophilic granulocytes and macrophages appeared. In addition, a distinct increase in B cells in spleens and lymph nodes was noted. Low levels of preformed antidonor antibodies did not increase during the first 48 h; however, significant amounts of species-, but not donor-, specific antibodies were demonstrated at the time of rejection. These data, together with the morphological observations, indicate a primarily humoral xenograft rejection in this model. Minor damage to graft myocytes a few hours after transplantation, progressing to vascular changes within 24-48 h, further suggests that preformed antidonor antibodies directed against endothelial or myocyte determinants may play an initiating role in the pathogenesis of unmodified, concordant xenograft rejection.

The distal nephron is preferentially infiltrated by inflammatory cells in acute interstitial nephritis

In acute interstitial nephritis (AIN), mononuclear cells invade the tubules (tubulitis). The segmental localization of tubulitis is not precisely known. To clarify this question, formalin-fixed kidney biopsy specimens from 13 patients with AIN were studied stereologically by identifying cortical tubules with segment-specific markers. The periodic acid-Schiff reaction, peanut lectin, and antibodies against Tamm-Horsfall protein and epidermal cytokeratins all applied to the same section were used to identify the proximal tubules (PTs), distal convoluted tubules, distal straight tubules, and the cortical collecting system (connecting tubules and cortical collecting ducts), respectively. Morphometrically, an estimate of the relative volume of the inflammatory cell infiltrates within each category of tubular segments was obtained. Inflammatory cells were infrequently found in PTs (1.2%) but were frequently localized in distal tubules and the cortical collecting system (7.6%). There was no difference in the amount of the inflammatory cell infiltrate within these segments. Re-examination of an electron microscopic study of AIN carried out in this laboratory revealed that mononuclear cells were rarely seen in convoluted PTs but were frequently observed in straight PTs and all segments distal to them. The observations indicate that it is the distal nephron which is primarily affected by inflammatory cell infiltration in AIN.

Monoclonal antibody treatment (anti-CD4 and anti-interleukin-2 receptor) combined with cyclosporin A has a positive but not simple dose-dependent effect on rat renal allograft survival

The use of monoclonal antibodies (MoAbs) in experimental and clinical organ transplantation is of increasing interest since this treatment seems to offer an opportunity for specific immunomodulation. In a rat kidney allograft model, Cyclosporin A (CyA) treatment (12.5 mg/kg/d, day 0-14) was combined with murine anti-rat CD4 (MRC OX-38) and murine anti-rat IL-2R (MRC OX-39) MoAbs at doses of 100 or 300 micrograms/kg/d (day 0-7) and plasma concentrations of the murine MoAb were determined. In both groups receiving combined treatment with CyA and MoAb, graft survival was prolonged to an average of 65 days, compared to a graft survival of 9-10 days in non-treated recipients. Further, the data showed a beneficial effect of CyA + MoAb treatment versus CyA alone (graft survival 32 days). The threefold increased MoAb dose did not seem to improve graft survival or function. Treatment with OX-38 + OX-39 at a dose of 100 micrograms/kg/d each resulted in plasma levels of 280 ng/ml 14 days after transplantation. Corresponding values after the administration of 300 micrograms/kg/d were 1800 ng/ml in graft recipients as well as controls. These findings indicate that the effect of MoAbs in complex organ transplantation models is not simply dose dependent and that in vitro assays are of limited value in predicting the effect of a given MoAb when used in vivo. The determination of MoAb plasma levels, however, may be a useful tool in defining optimal MoAb administration and to monitor therapeutically effective plasma levels.

Flush perfusion of rabbit kidneys with autogeneic, allogeneic and xenogeneic blood

A simple perfusion model was developed to study the events that lead to rejection of renal xenografts. Flush perfusion of the kidneys of 24 rabbits was carried out with blood from rabbits, cats, or humans. Light microscopy showed alterations with neutrophilic granulocytes margination of the vessels after only 15 min of perfusion. In the experiments with human blood the immunofluorescence microscopy showed deposits of immunoglobulins and complement factor III. This simple method is therefore a useful way of studying perfusion in renal xenografts.

Nephrotoxicity of cyclosporin A in patients with newly diagnosed type 1 diabetes mellitus

Renal function was studied in 18 patients with Type 1 diabetes mellitus. All were participating in the Canadian-European randomized placebo-controlled cyclosporin trial in newly diagnosed Type 1 diabetic patients, nine being randomized to placebo, and nine to cyclosporin A. During treatment for 12 to 18 months, cyclosporin A caused significant reductions in the glomerular filtration rate (before drug withdrawal, cyclosporin 97 +/- 18 vs placebo 125 +/- 16 ml min-1 1.73-m-2, p less than 0.05), renal plasma flow (454 +/- 83 vs 536 +/- 70 ml min-1 1.73-m-2, p less than 0.05), and lithium clearance (17 +/- 3 vs 28 +/- 5 ml min-1 1.73-m-2, p less than 0.05). The fractional proximal reabsorption was increased (0.82 +/- 0.03 vs 0.78 +/- 0.03, p less than 0.05), and the fractional distal sodium reabsorption reduced (0.88 +/- 0.03 vs 0.94 +/- 0.02, p less than 0.05). These results are in accordance with the hypothesis that the nephrotoxic effect of cyclosporin A results from a preferential constriction of afferent glomerular vessels. One year after withdrawal of the drug, all variables were similar in the two groups, except for blood glucose control which was worse in the cyclosporin A treated group. When corrected for differences in blood glucose control it appeared that in three out of nine patients glomerular filtration rate had not completely returned to the reference range of the placebo group. We conclude that the nephrotoxic side-effects of cyclosporin A treatment for 1 year are reversible. There are, however, signs of minor and perhaps chronic renal injury.

Treatment with total lymphoid irradiation, cyclosporin A and a monoclonal anti-T-cell antibody in a hamster-to-rat heart transplantation model: graft survival and morphological analysis

Treatment with preoperative total lymphoid irradiation and post-transplant cyclosporin A has been shown to have a synergistic effect on graft survival in allo- and xenotransplantation. Specific monoclonal antibodies against T cells and T cell subpopulations could offer new ways of preventing graft rejection in xenotransplantation. Graft survival and histology were examined after total lymphoid irradiation plus cyclosporin A treatment versus cyclosporin A plus a monoclonal antibody in a concordant, heterotopic, hamster-to-rat heart transplantation model. Preoperative total lymphoid irradiation was given at a dose of 1.25 Gy, 12 times over a period of 3 weeks. Cyclosporin A at a dose of 12.5 mg/kg per day was administered perorally and OX-19, a pan T cell monoclonal antibody, was given as intraperitoneal injections at doses of 100 micrograms or 500 micrograms/kg per day from day 0 until graft rejection. While total lymphoid irradiation alone prolonged graft survival to 9.4 days, total lymphoid irradiation plus cyclosporin A extended graft survival to a mean of 22 days. Cyclosporin alone or combined with the monoclonal antibody could not increase graft survival significantly when compared to untreated animals, which rejected their grafts within 3.7 days. Vascular rejection was the characteristic morphological finding, even after some weeks of excellent graft function. In conclusion, total lymphoid irradiation and cyclosporin A had a synergistic effect on graft survival in this concordant xenotransplantation model, although recent impressive results from other groups could not be reproduced. Total lymphoid irradiation combined with cyclosporin A appears to delay a primary humoral graft rejection, while the mechanism of rejection, judged by histology, stays the same.

Hope for successful xenografting by immunosuppression with monoclonal antibody against CD4, total lymphoid irradiation and cyclosporine. Six months' survival of hamster heart transplanted into rat

Hamster hearts were transplanted to rats, and the effects of combinations of total lymphoid irradiation (TLI), cyclophosphamide, cyclosporine A (CyA) and monoclonal antibodies (MAB) were investigated. Controls not immunosuppressed rejected their xenograft in 3 to 5 days, while combination immunosuppression including MABs against CD4 or IL-2-receptors extended graft survival significantly. In one case, the graft was still functioning 180 days after transplantation, which is the longest survival seen in this model. The use of specific MABs may open a new era for both xeno- and allo-transplantation.

Mentor program for high school students

As the nation grapples with the latest shortage of registered professional nurses, a creative solution, with an eye toward nursing in the 21st century, is the Mentor Program in Nursing for high school students at The Mount Sinai Medical Center in New York City. The registered professional nurses on staff at the medical center have made a commitment to this program as a way of encouraging a continuous supply of future nurses.

High-level penicillin-resistant gonococcal infections in Port Elizabeth

The prevalence of penicillin-resistant Neisseria gonorrhoeae in black men with acute urethritis at two clinics for sexually transmitted diseases in Port Elizabeth was assessed during the latter half of 1986. Gonococcal aetiology was confirmed in 80% of 290 patients. Penicillinase-production was detected in 4.3% culture-positive cases, while intermediate penicillin resistance was demonstrated in another 28 isolates (13.9%). At least two strains exhibited high-level penicillin resistance without producing beta-lactamase. All isolates tested were susceptible to tetracycline and spectinomycin. The emergence of penicillin-resistant gonococci throughout southern Africa will require new approaches to the treatment of acute urethritis in men.

Corticosteroids in treatment of disseminated tuberculosis in patient with HIV infection

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