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BACKGROUND Although induction of durable mixed chimerism is required for murine skin allograft tolerance (TOL), renal allograft TOL has been achieved after induction of only transient mixed chimerism in nonhuman primates (NHPs) and humans. To better define the level/duration of chimerism required for stable renal allograft TOL, we retrospectively analyzed these parameters and compared them with transplant outcomes in NHP combined kidney and bone marrow transplant recipients. METHODS Peripheral blood levels and duration of myeloid or lymphoid chimerism were retrospectively analyzed in 34 NHP combined kidney and bone marrow transplantation recipients which were divided into 3 groups: TOL, n = 10; chronic antibody-mediated rejection (CAMR), n = 12; and T cell-mediated rejection (TCMR), n = 12. RESULTS All 4 of the recipients that failed to develop any chimerism lost their allografts due to TCMR after discontinuation of immunosuppression (56 ± 3 d). Among 30 recipients who successfully developed multilineage chimerism, 10 achieved long-term immunosuppression-free survival without rejection (1258 ± 388 d), 12 eventually developed CAMR (932 ± 155 d), and 8 developed TCMR (82 ± 10 d). The maximum level but not duration of lymphoid chimerism was significantly higher in TOL recipients compared with both CAMR (P = 0.0159) and TCMR (P = 0.0074). On the other hand, the maximum myeloid chimerism was significantly higher in TOL than in TCMR (P = 0.0469), but not in CAMR. Receiver operating characteristic analyses revealed that lymphoid chimerism levels of 3.1% or greater could reliably predict long-term immunosuppression-free renal allograft survival (P < 0.0001). CONCLUSIONS This retrospective study confirmed that induction of chimerism is essential for long-term immunosuppression-free survival, which best correlates with lymphoid chimerism levels higher than 3.1%.

Two patients with end-stage renal disease secondary to multiple myelomas were treated with combined kidney and bone marrow transplantation in an effort to achieve donor-specific allotolerance through the induction of mixed lymphohematopoietic chimerism.

Sickle cell intrahepatic cholestasis is a potentially fatal end-organ complication of sickle cell anemia. Renal involvement in sickle cell anemia is common, and in some cases, can present as acute renal failure. Although renal transplants have been performed in patients with sickle cell anemia since the late 1960s and a number of liver transplants have been recently performed for these complications, there has not been experience with dual organ transplantation for sickle cell anemia-related complications. We describe the case of a patient with sickle cell anemia who underwent successful combined liver and kidney transplantation after the development of acute sickle cell intrahepatic cholestasis and renal failure requiring continuous venovenous hemodialysis. The patient underwent a successful combined liver and kidney transplant with limited perioperative complications and preserved allograft function. At 22 months posttransplant, the patient expired as a result of an acute pulmonary embolus in the setting of bilateral hip fractures. Autopsy revealed no evidence of liver or kidney allograft rejection and evidence of chronic sickle cell nephropathy in the native kidney. Combined liver and kidney transplantation is a viable therapeutic option in patients with severe end-organ effects of sickle cell anemia.

Background. Pseudomonas aeruginosa is an uncommon cause of infection in the female genital tract. We report a case of postmenopausal tubo-ovarian abscess (TOA) due to P. aeruginosa in a renal transplant recipient. The presentation included mild abdominal symptoms with rapid progression of peritonitis and surgical abscess drainage. This is the first such case in an organ transplant recipient described in the English literature. Methods and Results. Published reports of 1040 cases of TOA were reviewed. The most common features were a history of sexually transmitted disease or pelvic inflammatory disease, and symptoms including abdominal pain and fever. Escherichia coli, Bacteroides spp., and Klebsiella pneumoniae were the most frequently encountered pathogens. Neisseria gonorrhoeae and Chlamydia trachomatis, which are frequently isolated from cervical cultures, are uncommonly isolated from tubo-ovarian abscesses. Forty percent of patients were treated with antibiotics alone, 18.8% with abdominal surgery, and 32% with surgery and antimicrobial therapy. Conclusion. This report illustrates the muted presentation and atypical microbiology of gynecologic infection in an organ transplant recipient.

Background. Recent studies suggest an association between diabetes mellitus and hepatitis C virus (HCV) infection. Our aim was to determine (1) the prevalence and determinants of new onset posttransplant diabetes mellitus (PTDM) in HCV (+) liver transplant (OLT) recipients, (2) the temporal relationship between recurrent allograft hepatitis and the onset of PTDM, and (3) the effects of antiviral therapy on glycemic control. Methods. Between January of 1991 and December of 1998, of 185 OLTs performed in 176 adult patients, 47 HCV (+) cases and 111 HCV (-) controls were analyzed. We reviewed and analyzed the demographics, etiology of liver failure, pretransplant alcohol abuse, prevalence of diabetes mellitus, and clinical characteristics of both groups. In HCV (+) patients, the development of recurrent allograft hepatitis and its therapy were also studied in detail. Results. The prevalence of pretransplant diabetes was similar in the two groups, whereas the prevalence of PTDM was significantly higher in HCV (+) than in HCV (-) patients (64% vs. 28%, P=0.0001). By multivariate analysis, HCV infection (hazard ratio 2.5, P=0.001) and methylprednisolone boluses (hazard ratio 1.09 per bolus, P=0.02) were found to be independent risk factors for the development of PTDM. Development of PTDM was found to be an independent risk factor for mortality (hazard ratio 3.67, P

UNLABELLED Development of mixed chimerism by donor bone marrow transplantation (DBMT) has led to long-term tolerance of solid organ allografts in nonhuman primates. As an initial attempt to extend this approach to cellular transplant, islet transplant from the same donor was attempted in the recipient previously made tolerant to a kidney allograft. METHODS After the conditioning with ATG, total body irradiation, thymic irradiation, and splenectomy, DBMT was performed followed by 4 weeks of cyclosporine. Kidney transplantation and native nephrectomies were subsequently performed on day 89. After 2.8 years of DBMT, diabetes was induced by streptozocin (STZ) and islets from bone marrow and kidney donor were transplanted without immunosuppression. RESULTS After DBMT, the recipient developed chimerism and no evidence of kidney rejection for more than 1000 days. STZ induced diabetes was reversed after the islet transplantation. Islet biopsies demonstrated insulin staining without rejection. Although the recipient became diabetic 300 days after islet transplantation, viable transplanted islets were found in the liver and under the kidney capsule without any evidence of rejection. CONCLUSION Tolerance with a nonmyeloablative conditioning can allow successful pancreatic islet transplantation without immunosuppression. Because no histological evidence of rejection was identified, recurrent diabetes is presumed to be inadequate islet mass.

Background. Complement activation has recently been implicated as a contributing factor to early and late allograft dysfunction in cardiac transplantation. The current study was designed to determine whether measurement of plasma complement fragments C4d and SC5b-9 would be useful in detecting acute rejection or accelerated graft atherosclerosis (AGA) in cardiac allograft recipients. Methods. We measured complement activation products, C4d (classical pathway) and SC5b-9 (terminal pathway), at the time of routine endomyocardial biopsy in heart transplant recipients. Ten patients in the immediate posttransplantation period (0-100 days) and 19 patients more than 6 months after transplantation were studied. Results. No correlation was found between plasma levels of complement activation fragments and the presence of biopsy-proven acute allograft rejection or AGA (assessed by coronary angiography). However, plasma C4d and SC5b-9 were significantly elevated in 9 of 10 and 7 of 10 patients, respectively, in the immediate posttransplantation period. This was followed by progressive decrease in the levels of C4d and SC5b-9 fragments during the first 4-6 weeks after transplantation. Conclusion. We conclude that measuring plasma levels of fragments C4d and SC5b-9 is not a useful noninvasive method for detecting acute rejection or AGA after heart transplantation. However, this study provides further evidence that early complement activation after heart transplantation may play a pathogenic role in allograft injury.

Background. Nonmyeloablative T cell depletion followed by donor bone marrow infusion has proved to be an effective approach to induction of mixed chimerism and tolerance of organ allografts in non-human primates. To help define the mechanisms involved we have compared T cell depletion with ATG versus anti-CD2 monoclonal antibody with respect to establishment of mixed chimerism and induction of tolerance. Background. Method. Background. Both nonmyeloablative regimens included low dose total body irradiation (1.5 Gy x 2), thymic irradiation (7 Gy), splenectomy and kidney plus donor bone marrow transplantation, followed by a 4-week posttransplant course of cyclosporine. In addition, the ATG group (13 recipients) received antithymocyte globulin, although the LOCD2b group (10 recipients) were treated with an anti-CD2 monoclonal antibody (LOCD2b). Results. In the ATG group, 11 of 13 monkeys developed multilineage chimerism and 9 survived for more than 100 days without kidney allograft rejection. In contrast, 0/10 monkeys in the LOCD2b group developed chimerism, 5 died of infection and 5 suffered progressive rejection; only 1 recipient survived beyond 100 days. Sequential monitoring of peripheral blood mononuclear cells revealed greater T cell (CD3+) depletion in the LOCD2b-treated animals compared to those receiving ATG. However, NK cells (CD16+CD8+) were significantly more depleted in the ATG group and NK function remained abrogated longer after ATG than LOCD2b treatment (3 weeks vs. Conclusion. Despite excellent T cell depletion by LoCD2b, ATG was more effective in inducing chimerism and tolerance. This difference correlated with anti-NK activity of the two reagents. These data suggest that NK cells may also resist engraftment of allogeneic bone marrow cells in this model.

Background. The optimal regimen for the prevention and treatment of cytomegalovirus (CMV) disease in solid organ transplant recipients remains to be defined, particularly for patients with abnormal or changing renal function. Methods. A prospective trial was conducted in patients receiving i.v. ganciclovir using a standardized dosing nomogram that corrects for renal function. Steady state peak (P) and trough (T) serum levels were determined by high-performance liquid chromatography and correlated with therapeutic outcomes and toxicities attributable to ganciclovir. Results. Over the study period, 44 individuals received ganciclovir prophylaxis (5 mg/kg/day) and 25 patients were treated (5 mg/kd q12 hr) for symptomatic CMV disease. Ganciclovir levels (mg/ml6SD) achieved in prophylaxis were P: 7.9863.34, T: 3.0362.63; and in treatment were P: 9.0063.72, T: 2.6561.82. Despite corrections for renal dysfunction, undialyzed patients with serum creatinine >3.0 mg/dl had trough levels in excess of the population mean (T: range 3‐ 8 mg/ml). Failure of prophylaxis (disease) or therapy (relapse) occurred in 14 patients; 8 of these were at risk for primary infection (donor CMV seropositive, recipient seronegative, P 3.0, 1.25 mg/kg QOD for Cr >5.0). Some groups of transplant recipients may require more intensive anti-CMV regimens. Cytomegalovirus (CMV*) is a major cause of morbidity in solid organ transplant recipients (1‐9). In various series, between 20 and 70% of organ transplant recipients are affected by CMV infection (2, 10 ‐12). Ganciclovir, in both i.v. and oral formulations, is commonly used to prevent and to treat CMV infection, although the optimal dose and duration of therapy have not yet been completely defined (13‐21). In clinical practice, patients requiring prophylaxis or treatment for CMV infection often have abnormal or fluctuating renal function. This is particularly relevant in the setting of recent organ transplantation or during acute renal allograft rejection. However, few data are available on which to base decisions about the dosing of ganciclovir in such patients (22‐23). In the attempt to optimize antiviral therapy in solid organ transplant recipients with variable renal function, a prospective study was performed to study blood levels and clinical outcomes associated with the routine administration of i.v. ganciclovir based on a standardized nomogram. Peak and trough serum ganciclovir levels were measured by highpressure liquid chromatography. An attempt was made to assess the dosing of ganciclovir and to assess the impact of dosage and serum levels on the efficacy and toxicities of antiviral therapy and any impact that might be detected with the use of prophylactic or therapeutic ganciclovir on the development of or recurrence of symptomatic CMV infection.

Background. We have previously demonstrated that induction of mixed lymphohematopoietic chimerism resulted in donor specific renal allograft tolerance without the need for chronic immunosuppression in nonhuman primates. Here we have tested whether tolerance can be similarly induced for baboon to cynomolgus renal xenografts. Methods. After preconditioning with anti-thymocyte globulin (ATG), nonlethal total body irradiation, and thymic irradiation, cynomolgus monkeys underwent splenectomy, native nephrectomies, and baboon marrow and renal transplants. Postoperative cyclosporine was given for 28 days. Results. In Group 1 (n=2, survival=13, 14 days), both animals developed anti-donor immunoglobulin G, had biopsy findings consistent with humoral rejection, and showed rapidly progressive xenograft failure. In Group 2 (n=5, survival=1, 16, 33, 112, 190 days), 15-deoxyspergualine was added to the regimen (Day 0-13). In one long-term survivor, donor specific hyporesponsiveness was first observed (mixed lymphocyte culture [(MLR]) on Day 48. MLR reactivity returned on Day 64 together with the development of anti-donor antibody and subsequent xenograft failure on Day 112. Donor specific T-cell hyporesponsiveness was detected in the other long-term survivor for the first 133 days, after which a donor-specific skin xenograft was placed, (survival 24 days). Following the skin graft rejection, a rise in the MLR, development of anti-donor antibody and progressive rejection of the renal xenograft were observed. Conclusions. Antibody-mediated rejection seems to constitute the major difference between concordant xenografts and allografts. Addition of 15-deoxyspergualine for 2 weeks posttransplant extended concordant primate xenograft survival to 6 months without chronic immunosuppression. In contrast to the allogeneic model, renal transplant acceptance in this xenogeneic system was interrupted by placement of a donor-specific skin graft.

Background Multilineage chimerism and long-term acceptance of renal allografts has been produced in non-human primates conditioned with a nonmyeloablative regimen. Our study was undertaken to evaluate the immunological and pathological status of long-term survivors and to define the role of splenectomy and of the primarily vascularized kidney in the regimen. Method Monkeys were treated with the basic regimen, including: total body irradiation, thymic irradiation, antithymocyte globulin, donor bone marrow transplantation, and a 4-week course of cyclosporine after which no further immunosuppression was given. They were divided into four groups according to the timing of kidney transplantation (KTx) and splenectomy as follows; group A (n=13): KTx and splenectomy on the day of donor bone marrow transplantation (day 0); group B (n=3): KTx on day 0 without splenectomy; group C (n=7): splenectomy on day 0 but delayed KTx until 3 to 16 weeks post-donor bone marrow transplantation; group D (n=3): both splenectomy and KTx delayed until day 120 post-donor bone marrow transplantation. Results In group A, 11 of 13 monkeys developed chimerism and 9 monkeys achieved long-term survival of 4 to 70 months without evidence of chronic vascular rejection. Alloantibodies were detected in only one long-term survivor. In contrast, all three monkeys in group B developed alloantibodies and rejected their allografts. In group C, long-term survival without alloantibody production was observed in two of three monkeys that had developed chimerism. In group D, all three recipients were sensitized and rejected the kidney allografts rapidly after transplantation. Conclusions 1) Production of anti-donor antibody was prevented in most recipients that developed mixed chimerism in the regimens with splenectomy at the time of donor bone marrow transplantation. 2) If splenectomy is not included in the initial conditioning regimen, induction of B cell tolerance is less likely and the result is late onset of alloantibody production and allograft rejection. 3) Immediate transplantation of the kidney at the time of recipient conditioning is not essential for induction of donor specific hyporesponsiveness by bone marrow transplantation.

BACKGROUND: Mixed allogeneic hematopoietic chimerism has previously been reliably achieved and shown to induce tolerance to fully MHC-mismatched allografts in mice and monkeys. However, the establishment of hematopoietic chimerism has been difficult to achieve in the discordant pig-to-primate xenogeneic model. METHODS: To address this issue, two cynomolgus monkeys were conditioned by whole body irradiation (total dose 300 cGy) 6 and 5 days before the infusion of pig bone marrow (BM). Monkey anti-pig natural antibodies were immunoadsorbed by extracorporeal perfusion of monkey blood through a pig liver, immediately before the intravenous infusion of porcine BM (day 0). Cyclosporine was administered for 4 weeks and 15-deoxyspergualin for 2 weeks. One monkey received recombinant pig cytokines (stem cell factor and interleukin 3) for 2 weeks, whereas the other received only saline as a control. RESULTS: Both monkeys recovered from pancytopenia within 4 weeks of whole body irradiation. Anti-pig IgM and IgG antibodies were successfully depleted by the liver perfusion but returned to pretreatment levels within 12-14 days. Methylcellulose colony assays at days 180 and 300 revealed that about 2% of the myeloid progenitors in the BM of the cytokine-treated recipient were of pig origin, whereas no chimerism was detected in the BM of the untreated control monkey at similar times. The chimeric animal was less responsive by mixed lymphocyte reaction to pig-specific stimulators than the control monkey and significantly hyporesponsive when compared with a monkey that had rejected a porcine kidney transplant. CONCLUSION: To our knowledge, this is the first report of long-term survival of discordant xenogeneic BM in a primate recipient.

Background. Due to the limited supply and increased demand for donor livers, waiting times are progressively lengthening, which may lead to transplantation at more advanced and less cost-effective stages of disease. The purpose of this study was to evaluate the outcomes and hospital charges of liver transplantation during two recent eras to identify areas for providing more cost-effective care. Methods. A total of 144 primary liver allografts were performed from 1991 to 1996. Patient characteristics, outcome measures, and hospital charges were compared for patients receiving allografts between 1991 and 1993 (group A) versus those receiving grafts between 1994 and 1996 (group B) using unpaired Student t tests for continuous data and chi-squared tests for categorical data. Results. In comparing groups A and B, no significant differences in patient demographics, relative contraindications, or indication for transplantation existed; median waiting time from date of listing until transplant increased from 88 days to 159 days; and a shift in UNOS priority status at time of transplantation occurred, as the percentage of patients requiring inpatient care increased from 58% to 75% (P=0.034). Despite this, patient hospital and 1-year survival significantly improved from 75.0% to 90.3% (P=0.016), and from 68.1% to 88.9% (P=0.002), respectively. Total hospital charges, without correction for inflation, were $174,908

Background Xenotransplantation would provide a solution to the current shortage of organs for transplantation. Our group has been successful in inducing tolerance in mice and monkey models of allogeneic transplantation. The present study attempts to extend the same tolerance-inducing regimen to a pig-to-baboon organ transplantation model. Methods Nine baboons underwent a conditioning regimen (consisting of nonmyeloablative or myeloablative whole body and thymic irradiation, splenectomy, antithymocyte globulin, pharmacologic immunosuppression and porcine bone marrow transplantation [BMTx]), which has previously been demonstrated to induce donor-specific allograft tolerance in monkeys. In addition, immunoadsorption of anti-alphaGal antibody (Ab) was performed. Four of the nine baboons received pig kidney transplants (KTx), and one also underwent repeat transplantation with an SLA-matched kidney. Two received heterotopic pig heart transplants (HTx). Three baboons underwent conditioning without organ transplantation for long-term studies of natural Ab kinetics. Results In the three baboons that received the conditioning regimen without an organ transplant, immunoadsorption reduced Ab by approximately 90%, but recovery of Ab to pretreatment level or higher occurred within 7 days. In contrast, the level of Ab remained low after organ transplant. No Ab to pig antigens other than alphaGal was detected in any baboon before or after BMTx, KTx, or HTx. No graft succumbed to hyperacute rejection. KTx function began to deteriorate within 3-6 days, with oliguria and hematuria progressing to anuria, and the kidneys were excised after 3, 6, 9, 11, and 14 days, respectively. One HTx ceased functioning at 8 days; the second baboon died with a contracting HTx at 15 days. Features of coagulopathy and thrombocytopenia developed in all six transplanted baboons (high D-dimer, prolonged prothrombin time and partial thromboplastin time, and falling fibrinogen) resulting in serious bleeding complications in two baboons, one of which died on day 9. Donor organs showed progressive acute humoral rejection with deposits of IgM, IgG, and complement; a focal mononuclear cellular infiltrate was also observed. The ureter was the earliest structure of the KTx affected by rejection, with progression to necrosis. Conclusions This conditioning regimen prevented hyperacute rejection but was ineffective in preventing the return of Ab, which was associated with the development of acute humoral rejection with features of coagulopathy. No baboon developed anti-pig Ab other than alphaGal Ab. Further modifications of the protocol directed toward suppression of production of Ab are required to successfully induce tolerance to pig organs in baboons.

Background. OKT3 monoclonal antibody therapy results in an acute clinical syndrome (ACS) associated with the release of tumor necrosis factor and sequestration of neutrophils in the lungs. We have previously shown that inhibition of tumor necrosis factor does not completely eliminate OKT3-ACS, suggesting that other factors also contribute to the ACS. The current studies analyzed complement activation in vivo during the first hour after OKT3 administration. Methods. Renal (n=4) and lung (n=4) transplant recipients received OKT3 as treatment for rejection and induction therapy, respectively. Complement activation products C4d, Bb, iC3b, and SC5b-9 were measured by ELISA. Hemodynamic parameters were also monitored in the lung transplant recipients. Neutrophil expression of CD11a, CD11b, and CD18 was monitored by flow cytometry. Controls included patients receiving methylprednisolone for rejection (n=4), two adults with adult respiratory distress syndrome who received extracorporeal membrane oxygenation, and normal volunteers (n=5). P values less than 0.05 ( * ) were considered significant. Results. Increases in the plasma levels of C4d, Bb, iC3b, and SC5b-9 were observed in seven of eight patients after OKT3 administration. Mean values (n=8) at 0, 15, and 60 min (in μg/ml) were as follows-C4d: 1.865, 2.644 * , and 2.607 * ; Bb: 0.245, 0.411, and 0.385; iC3b: 10.881, 17.242 * , and 15.145 * ; and SC5b-9: 0.232, 0.269, and 0.302 * . An increase in CD11b and CD18 and a decrease of CD11a on neutrophils in parallel with complement activation was observed. In lung transplant recipients, C3 activation correlated with increases in mean pulmonary and central venous pressures (P

BACKGROUND Intravascular fibrin deposition and platelet sequestration occur with porcine xenograft rejection by baboons. Disseminated intravascular coagulopathy may arise either as a direct consequence of the failure to fully deplete xenoreactive natural antibodies and block complement, or because of putative cross-species molecular incompatibilities in this discordant species combination. METHODS Three baboons were conditioned with retrovirally transduced autologous bone marrow to induce tolerance to swine antigens. Xenoreactive natural antibodies and complement were depleted by plasmapheresis and the use of Gal alpha1-3Gal column adsorptions; baboons were then splenectomized and underwent renal xenografting from inbred, miniature pigs. Soluble complement receptor type-1 with protocol immunosuppression (mycophenolate mofetil, 15-deoxyspergualin, steroids, and cyclosporine) was administered. RESULTS A bleeding diathesis was clinically evident from days 5 to 12 after transplantation in two baboons. Low levels of circulating C3a, C3d, and iC3b were measured despite the absence of functional circulating complement components. Profound thrombocytopenia with abnormalities in keeping with disseminated intravascular coagulopathy were observed. Prolongation of prothrombin and partial thromboplastin times was accompanied by evidence for tissue factor-mediated coagulation pathways, high levels of thrombin generation (prothrombin fragment F(1+2) production and thrombin-antithrombin complex formation), fibrinogen depletion, and production of high levels of the fibrin degradation product D-dimer. Importantly, these disturbances resolved rapidly after the excision of the rejected xenografts in two surviving animals. Histopathological examination of the rejected xenografts confirmed vascular injury, fibrin deposition, platelet deposition, and localized complement activation. CONCLUSIONS Systemic coagulation disturbances are associated with delayed xenograft rejection.

Background, Organ transplant recipients who are seropositive for cytomegalovirus (CMV) and who are treated with antilymphocyte antibody (ALA) therapy have a high rate of symptomatic CMV disease. The intravenous administration of ganciclovir therapy once daily during ALA therapy decreased the incidence from 24% to 10% in patients receiving ALA as an induction therapy and from 64% to 22% in those treated for rejection. The present study was undertaken to determine whether a more intensive and sustained antiviral regimen could be more effective. Methods. From April 1995 to December 1997, all CMV seropositive renal and liver transplant recipients who received ALA therapy were treated with intravenously administered ganciclovir (5 mg/kg/day with dose adjusted for renal dysfunction) for the length of ALA therapy and then with orally administered acyclovir (400 mg three times/day) or ganciclovir (1 gm twice/day) for 3 to 4 months. The incidence of CMV viremia and of CMV disease was determined during the 6 months after completion of ALA therapy. Results. Forty-one patients (35 renal and 6 liver transplant recipients) were studied. CMV disease occurred in 2 patients (4.9%), both of whom were treated for rejection; it occurred in 1 of 21 patients (4.8%) treated with orally administered acyclovir, and in 1 of 20 patients (5%) treated with orally administered ganciclovir. The only patient who developed CMV disease in the ganciclovir group had received only 26 days of oral antiviral therapy. No CMV disease was documented in the group of patients receiving ALA therapy as induction therapy. CMV viremia occurred in three patients in the acyclovir group (14.3%) and in one patient in the ganciclovir group (5%). Among renal transplant recipients only, 1 of 35 patients developed CMV disease (2.9%) and no case of CMV disease was documented in patients treated with orally administered ganciclovir. All six patients receiving two courses of ALA therapy each were free of CMV disease. Toxicity of the regimen was minimal, and antiviral resistance did not develop. Conclusions. Preemptive antiviral therapy with intravenously administered ganciclovir during ALA therapy and then orally administered ganciclovir for 3 to 4 months provides virtually complete protection against the excessive rate of CMV disease that occurs in CMV seropositive allograft recipients receiving ALA therapy.

Fibrosing cholestatic hepatitis (FCH) has recently been described after solid organ transplantation in patients with hepatitis C virus (HCV) infection. Typically, FCH is characterized by an ominous clinical course leading to progressive hepatic failure and death if liver transplantation is not performed. Two HCV-infected patients underwent cadaveric renal transplantation for end-stage renal disease resulting from membranous nephropathy and diabetic nephropathy. The time intervals between transplantation and the biopsy diagnosis of FCH for the two patients were 7 months and 10 years. Both patients presented with jaundice, hyperbilirubinemia, and mild-to-moderate elevations in serum aspartate aminotransferase. One patient was also found to have type II mixed cryoglobulinemia. Interferon-α therapy was begun after a diagnosis of FCH was established by liver biopsy. Liver test abnormalities normalized rapidly. When cholestatic hepatic deterioration develops in an HCV-infected organ allograft recipient, the diagnosis of FCH should be considered and a liver biopsy performed. Our observations indicate that FCH can respond to antiviral therapy.

Background. Optimizing therapeutic monoclonal antibody (mAb) depends on the incorporation of the necessary effector functions and the development of hypoantigenic humanized antibodies by genetic engineering, which then need to be tested in appropriate preclinical trials. Methods. Constructs of humanized OKT4A containing the complementarity-determining region (CDR) of murine OKT4A and the framework and constant regions of human light (κ) and heavy chains (IgG1 and IgG4) were prepared and tested in cynomolgus monkeys who received a renal allograft. A prophylactic course of CDR-OKT4A/human (h) IgG1 or CDR-OKT4A/ hIgG4, either as high-dose single bolus (10 mglkg) or as low-dose multiple infusion (1 mglkg for 12 days) was given, and the effects on graft survival, immunohistology, circulating cells, and lymph node cells were assessed. Results. The IgG1 isotype induced coating of T cells, modulation of surface CD4 molecules, and profound depletion of CD4 + lymphocytes in peripheral blood, which persisted as long as the animals were followed (up to 7 weeks). The IgG4 isotype induced only cell coating without cell clearance or modulation. In lymph nodes, coating of lymphocytes (approximately 60%) was seen with both isotypes in the earliest sample (6 hr). After 2 days, significant depletion of lymph node CD4 cells was evident, with a decrease in the CD4 to CD8 ratio in the IgG1-treated group; no depletion occurred in the IgG4 group. The emigration of CD4 + cells into the allograft was significantly delayed in the CDR-OKT4A/hIgG1-treated animals when compared with the CDR-OKT4A-hIgG4 group as judged by immunocytochemistry 123.8±13.2 days vs. 7.4±1.5 days, P

BACKGROUND Combined kidney-pancreas transplantation (CKPT) with its associated euglycemia has been shown to prevent or reduce recurrent diabetic nephropathy in the renal allograft. There has been no evaluation of residual native kidney function after CKPT. The purpose of this study was to determine whether native kidney function may be present in diabetic recipients years after CKPT. METHODS Between 1986 and 1992, 37 patients with type 1 insulin-dependent diabetes mellitus with renal failure underwent CKPT. In each case, a single native nephrectomy was performed. We studied 16 patients who had continuing renal and pancreas function more than 4 years after CKPT. Fourteen diabetics with a functioning renal allograft but no pancreas function were used as a control group. Simultaneous renal scans (technetium-99m diethylenetriamine pentaacetic acid) of the native and transplanted kidneys were obtained with a dual-head scintillation camera. Total glomerular filtration rate (GFR) was determined from the rate of clearance of the tracer from the extracellular space measured for 2 hr with an ambulatory renal monitor. RESULTS The study groups had similar pretransplant characteristics. At the time of the study, the mean serum creatinine level was not significantly different in the CKPT and control groups (1.7+/-0.7 vs. 1.5+/-0.3 mg/dl, respectively). In the CKPT and control groups, total GFRs were 70.1+/-33 vs. 72.1+/-16.5 ml/min (NS), allograft GFRs were 63+/-34.2 vs. 70.4+/-16 ml/min (NS), and native kidney GFRs were 7.1+/-7.2 vs. 1.7+/-1.9 ml/min (P < 0.05), respectively. In both groups, there was a significant correlation between total GFR and allograft GFR (P < 0.001), but not between total GFR and native kidney GFR. Significant single native kidney GFR (more than 8 ml/min) was found in 7/16 (44%) patients in the CKPT group, but in none of the controls. CONCLUSIONS These results suggest that residual native kidney function can be present and contribute moderately to total GFR after CKPT. Euglycemia after CKPT may have a protective role in native kidneys.

Background. Hepatic artery thrombosis (HAT) remains a devastating complication after liver transplantation. Various factors have been implicated in the pathogenesis of HAT, such as clotting abnormalities, increased hematocrit, and technical complications, but the role of anticardiolipin antibodies has not been evaluated. We investigated the possible association between HAT and anticardiolipin antibodies in adult patients who underwent liver transplantation. Methods. Seven patients with HAT after orthotopic liver transplantation, 28 liver recipients without HAT, and 35 normal blood donors were evaluated. Determination of IgM and IgG anticardiolipin antibodies was performed by enzyme-linked immunosorbent assay using pretransplant serum from all allograft recipients. Clinical information was obtained from chart review. Fisher's exact test and Wilcoxon rank sum test were used for statistical analysis, and all P-values were two-tailed. Results. Overall, 22 of 35 (63%) liver recipients had a positive anticardiolipin antibody test (either IgG or IgM titer >4 SD from the normal controls). The test was positive in 7 liver recipients (100%) with HAT compared with 15 out of 28 patients (54%) without HAT (P=0.031). As compared with liver recipients without HAT, patients with HAT also tended to have a higher mean anticardiolipin titer of IgG and IgM and a lower pretransplant platelet count; however, these differences were not significant. Conclusions. Our findings indicate that anticardiolipin antibodies are frequently elevated in patients with liver failure and may contribute to the pathogenesis of HAT after liver transplantation. Other potential consequences of anticardiolipin antibodies in end- stage liver disease remain to be determined.

In recent years, hepatitis C virus infection has been reported to be typically associated with membranoproliferative glomerulonephritis and less frequently with membranous nephropathy. Treatment of hepatitis C with interferon-alpha can reduce viremia and improve renal disease. After liver transplantation for hepatitis C virus-associated liver failure, standard immunosuppressive protocols result in a significant increase in hepatitis C viremia. In this report we describe a patient with end-stage liver disease and biopsy-proven hepatitis C-associated glomerulonephritis who underwent liver transplantation. Within 1 month after transplantation, he developed a severe nephrotic syndrome that paralleled a marked increase in viremia. We discuss the possible pathogenic relationship between hepatitis C virus infection and the nephrotic syndrome that followed liver transplantation.

Background We demonstrated previously that a nonmyeloablative preparative regimen can induce mixed chimerism and allograft tolerance in cynomolgus monkeys. Methods The current studies were designed to clarify the importance and toxicity of various elements of the allotolerance conditioning regimen by: fractionating or reducing the whole-body irradiation (WBI) dosage; adding deoxyspergualine; or deleting donor bone marrow, cyclosporine, irradiation, or splenectomy. Results Monkeys treated without donor bone marrow, cyclosporine, or irradiation did not develop chimerism or long-term allograft survival. One of three monkeys treated without splenectomy developed chimerism but died of a surgical complication. The other two did not develop chimerism and rejected by day 117. Six of six monkeys treated with 300 cGy of fractionated WBI developed chimerism. Five of these recipients had long-term graft survival. Only two of four monkeys treated with 250 cGy developed chimerism, so a 2-week course of deoxyspergualine was added. This led to chimerism in two monkeys, but one died of ureteral stenosis and the other died of allograft rejection. An unanticipated high incidence of ureteral complications felt to be secondary to rejection episodes and ischemic injury was observed in the long-term surviving animals. Conclusions All parameters of the original preparative regimen seem to be essential for consistent success. The degree of lymphocyte depletion was proportional to the WBI dose. Long-term graft survival was observed only in recipients achieving lymphocyte chimerism of > 1.5%. In this model, lymphocyte depletion seems to be the best predictor of chimerism, and significant lymphocyte chimerism seems to be important in achieving tolerance.

We report a case of accelerated acute rejection of a renal allograft from a presumed ABO histo-blood group A2 donor in an O recipient, in which all of the published criteria for compatibility had been met. Flow cytometric analysis of the A and H antigen expression on the kidney donor's erythrocytes suggested that this donor did not have an A2 phenotype, but rather another subgroup of A. Some of the reported cases of accelerated acute rejection of A2 renal allografts in O recipients may have resulted from misapplication of the results of standard lectin agglutination to the transplant setting. The current case suggests that a more sophisticated method of ABO phenotyping, such as erythrocyte flow cytometric analysis, may be necessary in the transplant setting.

Tumor necrosis factor alpha (TNFa) has been shown to be the primary cytokine responsible for the OKT3-induced acute clinical syndrome (OKT3-ACS). Recombinant human soluble tumor necrosis factor receptor (TNFR :Fc) is a dimer of the p80 TNF receptor, which binds both TNFa and lymphotoxin (LT). Renal allograft recipients undergoing OKT3 therapy for steroid-resistant rejection were randomized to receive OKT3 alone or in combination with TNFR :Fc to determine its safety and efficacy in decreasing the severity of OKT3-ACS and in restoring renal function. Six of 12 patients were given TNFR :Fc prior to each of the first two injections of OKT3. All patients were monitored for manifestations of OKT3-ACS and changes in renal function. In addition, serial serum samples were assayed for TNFa and TNFR :Fc levels (ELISA) and TNFa bioactivity (L929). No adverse side effects were identified in patients receiving TNFR :Fc. Patients treated with TNFR :Fc had significantly fewer symptoms by day 2 of OKT3, and had a lower overall incidence of chills and arthralgias. Renal dysfunction reversed Within 24 hr in the TNFR :Fc-treated group in contrast to the 48-72-hr delay in the control group. Antigenic TNFa levels increased in the control group from

We have developed a nonmyeloablative preparative regimen that can produce mixed chimerism and renal allograft tolerance between MHC-disparate nonhuman primates. The basic regimen includes ATG, nonmyeloablative total-body irradiation (TBI, 300 rads), thymic irradiation (TI, 700 rads), and donor bone marrow infusion. Kidney allografts from MHC-mismatched donors were transplanted with various manipulations of the preparative regimen. Monkeys treated with the basic regimen alone (n = 2) rejected allografts by day 15. With the addition of cyclosporine (CsA) for one month (n = 3), one monkey developed multilineage mixed chimerism and renal allograft tolerance thereafter (> 430 days). To reduce the toxicity of the preparative regimen, TBI was fractionated to 150 rads on two successive days in subsequent studies. All monkeys receiving this modified regimen (n = 4) developed multilineage chimerism with fewer side effects and accepted renal allografts long-term with no further immunosuppression (196 days, 198 days, > 150 days, and > 40 days). In long-term survivors, donor-specific nonreactivity was confirmed by MLR and skin transplantation. Three monkeys treated with the basic regimen plus CsA but with only 150 rads of TBI (n = 1) or no TBI (n = 2) did not develop multilineage chimerism and grafts were rejected (day 40-50) soon after the CsA discontinuation. Monkeys treated with the same regimen, but without DBM (n = 2), rejected kidney allografts by day 52. Therefore, at least transient engraftment of DBM appears to be essential for induction of donor specific tolerance in this monkey model.

Because of the almost universal recurrence of hepatitis B surface antigenemia (HBsAg) after liver transplantation, some centers have questioned whether these patients are appropriate allograft candidates. Since January 1984, 51 patients with hepatitis B (HBV) underwent OLT at our center. No therapy was given to prevent reinfection. Three patients underwent retransplantation. The indications for transplant included fulminant HBV (13 patients), chronic HBV (33 patients), and hepatocellular carcinoma (HCCA) in addition to HBV (5 patients). Incidental HCCA was found in 2 of the 33 patients thought to have only chronic HBV. Actuarial survival for the entire group was 57% at 1 year and 54% at 3 years. Of the 23 patients who died, only 4 deaths were attributable to recurrent HBV liver disease. Four patients survived less than 4 days due to primary graft nonfunction. Ten patients died in the first 3 months from sepsis. Although all patients who died beyond 30 days had recurrent HBsAg, only 4 deaths were attributable to recurrent HBV. The remaining 5 deaths were caused by portal vein thrombosis, bile leak, lymphoma, pancreatitis, and sepsis occurring at 15 months. Excluding the 4 patients who died from primary graft nonfunction, actuarial survival was 63% at 1 year and 60% at 3 years. Of the 28 survivors, 24 are HBsAg positive; however, only 5 have recurrent HBV liver disease. Multiple factors were evaluated to determine their influence on survival; i.e., HBV serology, United Network for Organ Sharing status, fulminant versus chronic HBV, incidence of rejection, immunosuppression, transfusion requirements, and presence of HCCA. Of these, only the presence of HCCA adversely affected outcome. Of the 7 patients with HCCA and HBV, 6 patients died within the first 6 months and 1 patient has recurrent HBV liver disease at 25 months. Actuarial survival excluding those patients with HCCA was 64% at 1 year and 61% at 3 years. Based on our results, patients with HBV and associated HCCA have a poorer prognosis and should probably be excluded from transplantation. Although the survival for patients with HBV undergoing liver transplantation is inferior to that expected in patients with some other diagnoses, long-term survival can be achieved in a majority of these patients despite recurrence of HBsAg. We believe that appropriately selected patients with a diagnosis of HBV alone should continue to be candidates for liver allografts.

In an attempt to improve therapeutic efficacy and limit antimurine responses to the IgG2a monoclonal antibody OKT4A, humanized complementarity determining region (CDR)-grafted OKT4A mAbs (IgG1 and IgG4 isotypes) were developed from the murine molecule. Preclinical evaluation was undertaken in 12 cynomolgus renal allograft recipients (IgG1, n = 7; IgG4, n = 5). Control animals received either no therapy (n = 2) or OKT3 (n = 2). The mAbs were given as a single 10-mg/kg bolus on the day of transplantation or as multiple 1-mg/kg doses. Mean allograft survival (+/- SEM) was 9 +/- 0.7 days in control animals; 45.2 +/- 6.0 days, P = 0.002 (single dose, n = 5), and 39 +/- 5.0 days, P = 0.053, (multiple doses, n = 2) in IgG1-treated animals; and 35.3 +/- 7.2 days, P = 0.034, (single dose, n = 3) and 15.5 +/- 6.5 days, P = .251 (multiple doses, n = 2) in IgG4-treated animals. Whereas IgG4-treated animals showed coating of peripheral blood CD4+ T cells, significant CD4+ T cell depletion was observed in IgG1-treated animals. These results confirm the retained immunosuppressive efficacy of humanized OKT4A antibodies. In contrast to murine mAbs, the use of these agents would not preclude sequential treatment with mAbs directed against different epitopes. The fact that rejection can occur despite peripheral blood CD4+ cell depletion suggests that indefinite control of allograft rejection in primates may require more intensive therapy than has proved effective in rodent models.

Hepatic retransplantation (reTx) offers the only alternative to death for patients who have failed primary hepatic transplantation (PTx). Assuming a finite number of donor organs, reTx also denies the chance of survival for some patients awaiting PTx. The impact of reTx on overall survival (i.e., the survival of all candidates for transplantation) must therefore be clarified. Between 1983 and 1991, 651 patients from the New England Organ Bank underwent liver transplantation, and 73 reTx were performed in 71 patients (11% reTx rate). The 1-year actuarial survival for reTx (48%) was significantly less than for PTx (70%, P0.05). This survival varied, dependent on the interval of time following PTx in which the reTx was performed (0-3 days, 57% survival; 4-30 days, 24%; 30-365 days, 54%; and365 days, 83%). Patients on the regional waiting list had an 18% mortality rate while awaiting transplantation. These results were incorporated into a mathematical model describing survival as a function of reTx rate, assuming a limited supply of donor livers. ReTx improves the 1-year survival rate for patients undergoing PTx but decreases overall survival (survival of all candidates) for liver transplantation. In the current era of persistently insufficient donor numbers, strategies based on minimizing the use of reTx, especially in the case of patients in whom chances of success are minimal, will result in the best overall rate of patient survival.

Significant differences in cellular responses were found among allograft recipients treated with various OKT4A mAb protocols. Recipients of multiple infusion low-dose and 2-bolus OKT4A immunosuppressive regimens regularly showed potent donor-specific cytotoxic CD8+ and CD4+ intragraft T cells and donor-reactive PBMC in MLC tests. In contrast, PBMC isolated from recipients of high-dose OKT4A therapy generally showed very weak or no response to donor-antigens during the later posttransplant periods. Furthermore, an absence of IL2-responsive intragraft cells was found to correlate with stable graft function in these recipients. We conclude that OKT4A mAb, in high doses, can block allosensitization and induce donor-specific nonresponsiveness in vivo. An OKT4A-based therapy, therefore, may have the potential of inducing long-lasting donor-specific immunosuppression, or even tolerance.

Although early survival following transplantation for primary hepatic cancer is excellent, previously reported high recurrence rates have generally discouraged liver replacement for this indication. Since the inception of the Boston Center for Liver Transplantation (BCLT) in 1983, 33 of 383 (8.6%) liver allograft recipients have undergone orthotopic transplantation as definitive treatment for otherwise unresectable cancer. Diagnoses included hepatocellular carcinoma (HCCA) in 24 patients (73%), and cholangiocarcinoma (CHCA) in 9 patients (27%). Actuarial survival rates for patients with hepatocellular carcinoma were 71%, 56%, and 42% at 1, 2, and 3 years, respectively. The actuarial survival rates for patients with cholangiocarcinoma were 89% at 6 months, and 56% at 1, 2, and 3 years. Of the nine patients with cholangiocarcinoma, 56% (5/9) developed recurrent disease. Although this recurrence rate is disheartening, because of the lack of other morbidity, long-term survival in these patients is comparable to patients with HCCA. In contrast, recurrent hepatocellular carcinoma developed in 25% of recipients (5/20) who survived longer than 3 months posttransplantation. Other causes of death in patients with hepatocellular carcinoma included perioperative complications, 16.6% (4/24); sepsis, 8.3% (2/24); coronary artery disease, 4.2% (1/24); and lymphoma, 4.2% (1/24). Favorable prognostic factors included: primary tumor less than 3 cm in size and absence of associated cirrhosis. These results emphasize that orthotopic liver transplantation can provide a long-term cure for approximately 50% of patients whose primary hepatic malignancy is unresectable by conventional procedures.

A prospective study to investigate risk factors for CMV disease was conducted in 94 renal transplant recipients. CMV disease was defined as either unexplained fever for greater than 3 days with viremia or unexplained fever for greater than 3 days with isolation of CMV from the urine or throat wash and at least one of the following: leukopenia, elevated serum alanine aminotransferase, or biopsy-proved invasive tissue infection of the lung or gastrointestinal tract. Fifty-three patients received immunosuppressive regimens consisting of prednisone and cyclosporine, with or without azathioprine. The remaining 41 patients were treated with these agents plus OKT3 (21 received OKT3 to treat rejection, 20 received OKT3 prophylactically). Thirty-seven patients were at minimal risk of CMV disease (donor and recipient seronegative for CMV); 12 patients were at risk of primary disease (donor seropositive, recipient seronegative), and 45 were at risk of reactivation disease (recipient seropositive at the time of transplantation). The incidences of CMV disease in the 3 groups were 0%, 58%, and 36%, respectively. Although the incidence of CMV disease in patients at risk of primary disease was not influenced by the immunosuppressive regimen, immunosuppression had a profound effect on the occurrence of CMV disease in CMV-seropositive transplant recipients. The incidence of CMV disease in those receiving OKT3 was 59%; but only 21% in those who did not receive OKT3. OKT3 increased the risk of CMV disease five-fold (odds ratio 5.2 (95% confidence limits 1.4-17.5)). In the CMV-seropositive patient, OKT3 was also the most important predictor of CMV disease by multivariate analysis (P less than 0.002). A pilot study of preemptive therapy with ganciclovir (2.5 mg/kg daily during OKT3 therapy) in 17 patients decreased the incidence of CMV disease without appreciable toxicity.

Evaluation of whole-organ pancreas transplantation in the therapy of IDDM has been difficult because of generally poor graft survival and significant complications in past experience. We report a technically successful simultaneous pancreas/kidney transplant program with patient and graft survival of 85% over 3 years of follow-up (mean 21 months) in 33 subjects with IDDM. Glucose metabolism was normalized without need for exogenous insulin immediately posttransplant in all but one recipient and remained normal in 85% of recipients. The outcome in pancreas/kidney recipients was compared with that in 18 insulin-dependent diabetic recipients of kidney transplant only performed in the same period. Quality of life was assessed with one general and one diabetes-specific questionnaire. General quality of life issues improved significantly in both pancreas/kidney and kidney recipients, but diabetes specific quality of life improved only in the pancreas/kidney recipients. Pancreas/kidney recipients required twice as long a period of hospitalization for the transplant and two times as many readmissions for a variety of complications. Only a minority of hospital admissions was strictly attributable to the pancreas graft. Of the five deaths in the pancreas/kidney recipients, two were attributable to the pancreas transplant. Pancreas transplantation in IDDM can now be accomplished with a high degree of success, resulting in normalized glucose metabolism and with overall mortality similar to kidney transplantation alone. Successful pancreas transplantation improves quality of life with respect to diabetes but this benefit is accomplished at a cost of increased hospital admissions and complications related to the transplanted pancreas. The effects of pancreas transplantation on the long-term complications of insulin-dependent diabetes remain unknown.

BK virus is a human polyomavirus associated with a range of clinical presentations from asymptomatic viruria with pyuria to ureteral ulceration with ureteral stenosis in renal transplant patients or hemorrhagic cystitis in bone marrow transplant recipients. Infection of renal allografts has been associated with diminished graft function in some individuals. Fortunately, however, the majority of patients with BK virus infections are asymptomatic. The type, duration, and intensity of immunosuppression are major contributors to susceptibility to the activation of BK virus infection. Histopathology is required for the demonstration of renal parenchymal involvement; urine cytology and viral polymerase chain reaction methods are useful adjunctive diagnostic tools. Current, treatment of immunosuppressed patients with polyomavirus viruria is largely supportive and directed toward minimizing immunosuppression. Improved diagnostic tools and antiviral therapies are needed for polyomavirus infections.

The effect of long-term pharmacologic immunosuppression (PI) on anti-Galalpha1-3Gal (alphaGal) antibody (Ab) levels has not been determined previously in humans. In this study, we measured alpha Gal Ab levels by ELISA in 14 healthy volunteers (controls) and in 70 patients with grafts (kidney, heart, liver) who had received different combinations of PI (including cyclosporine, tacrolimus, azathioprine, mycophenolate mofetil, and steroids) for3 months. There was great variation in Gal IgM (80-fold) and IgG (160-fold). There was no difference in Gal IgM or Gal IgG between any one group and any other. In kidney patients with either high (mean 68%) or low (mean 6%) panel-reactive alloantibodies, there was no difference in alpha Gal Ab level or serum cytotoxicity to pig cells. In vitro immunoadsorption of alphaGal Ab from the serum did not change panel-reactive alloantibody positivity. Therapy with OKT3, a mouse product that might stimulate alphaGal Ab production, led to no significant change in patient Ab levels. We conclude that long-term (3 months) PI does not reduce Gal Ab levels sufficiently to be of clinical value in xenotransplantation.

Background Experimental and clinical evidence has demonstrated that the establishment of allogeneic chimerism after bone marrow transplantation may provide donor-specific tolerance for solid organ allografts. Methods Based on the preliminary results of a clinical trial using nonmyeloablative preparative therapy for the induction of mixed lymphohematopoietic chimerism, we treated a 55-year-old woman with end stage renal disease secondary to multiple myeloma with a combined histocompatibility leukocyte antigen-matched bone marrow and renal transplant after conditioning with cyclophosphamide, antithymocyte globulin, and thymic irradiation. Results The posttransplant course was notable for early normalization of renal function, the absence of acute graft-versus-host disease, and the establishment of mixed lymphohematopoietic chimerism. Cyclosporine, which was the only posttransplant immunosuppressive therapy, was tapered and discontinued on day +73 posttransplant. No rejection episodes occurred, and renal function remains normal on day + 170 posttransplant (14 weeks after discontinuing cyclosporine). Although there is presently no evidence of donor hematopoiesis, there is evidence of an ongoing antitumor response with a recent staging evaluation showing no measurable urine kappa light chains. The patient remains clinically well and is off all immunosuppressive therapy. Conclusion This is the first report of the deliberate induction of mixed lymphohematopoietic chimerism after a nonmyeloablative preparative regimen to treat a hematological malignancy and to provide allotolerance for a solid organ transplant.

Several adhesion molecules contribute to the interaction between T cells and antigen presenting cells or target cells. Leukocyte function-associated molecule-1 (LFA-1[CD11a/CD18]) and intercellular adhesion molecule-1 (ICAM-1 [CD54]) are one such critical adhesive receptor-counter-receptor combination. The importance of ICAM-1 dependent adhesion in the rejection response was initially demonstrated in cynomolgus renal allograft recipients treated with the anti-ICAM-1 murine monoclonal antibody BIRR1. BIRR1 also appeared to limit ischemic damage in these animals. A Phase I clinical trial has subsequently been completed in 18 patients who received cadaver donor renal allografts at high risk for delayed graft function (prolonged preservation time, highly-sensitized recipient). An adequate BIRR1 serum level was associated with significantly less delayed graft function (P.01) and rejection (P.01). In 1-hr biopsies, mouse IgG was detected along the endothelium of the vessels and glomeruli in the graft. There were no instances of primary non-function (PNF), and current allograft survival (followup: 16-30 months) in these "high-risk" mAb-treated patients is 78%. There were 3 instances of PNF and a graft survival rate of 56% in the recipients of the contralateral kidney allografts treated with conventional immunosuppression. No significant "first-dose" effect was associated with BIRR1 administration. These results establish a dosing schedule and the clinical safety of BIRR1. They also suggest that inhibition of leukocyte adhesion by mAb therapy may be useful in controlling allograft rejection and possibly in limiting reperfusion injury. Thus, these observations support the clinical importance of accessory molecules in T cell function. We hypothesize that anti-CD54 mAb acts by blocking leukocyte adhesion to the endothelium, thereby interfering with sensitization or target cell interaction.

A nonhuman primate antimurine response (MAMA) has been observed in 17 cynomolgus renal allograft recipients of murine OKT 4A. Neither cyclosporine, nor total-lymphoid irradiation, nor donor bone marrow preparation inhibited this antixenogeneic response. In an attempt to alter the antimurine basis of the response, a humanized chimeric OKT4A (IgG4) containing the entire variable portion of the murine OKT4A and a humanized CDR grafted OKT4A mAb sharing only the Complementarity Determining Region from the murine OKT4A, were administered to 8 cynomolgus allograft recipients. MAMA was detected in each recipient. In contrast to sera from recipients of murine OKT4A, sera from recipients of humanized OKT4A displayed no reactivity to other murine mAbs. MAMA specificity did not assay constant (C) region differences between the murine and humanized mAb; however, C region homology in humans should preclude a human antimouse antibody (HAMA) to the Fc portion of a humanized mAb. Furthermore, cynomolgus recipient serum levels of the humanized OKT4A mAb were maintained (> 1 microgram/ml) for a longer period than following treatment with murine OKT4A (murine < 12 days versus between 12 and 24 days for the humanized). If the HAMA response to humanized mAb in future clinical trials, were to be predictably anti-idiotypic, then the opportunity for treatment with sequential mAbs of differing idiotypes would be retained. Moreover, these current studies also suggest that humanized construction may influence the duration of therapeutic mAb levels. Thus, anti-idiotypic reactivity may not be as consequential to the clinical administration of humanized mAb to allograft recipients.