The immunosuppressive effect of FK 506 on canine lung transplantation.

The immunosuppressive potency of FK 506 was studied after left lung transplantation in adult mongrel dogs in comparison with cyclosporine. Fiberoptic bronchoscopy, bronchial mucosal blood flow measurement with laser Doppler velocimetry, and chest x-ray and pathologic examinations were performed. Group A had no immunosuppression (n = 5); group B received FK 506 (0.10 mg/kg/day intramuscularly (n = 5); group C received cyclosporine (20 mg/kg/day orally) (n = 5). In group A four dogs died of rejection on the seventh to the twenty-first postoperative days. Another one was killed on the fourteenth postoperative day because bronchial dehiscence occurred at the anastomosis. In group B one died of alveolar rejection on the seventh postoperative day. The remaining four survived 28 days and were put to death. In group C all five dogs survived 28 days and were put to death. In group A bronchial stenosis or dehiscence at the anastomosis was found in every one during the early postoperative period. In group B stenosis did not develop in any of the dogs, including the one that died on the seventh postoperative day. In group C slight stenosis was seen in one dog, severe narrowing in another, and good healing in the remaining three. The transplanted lungs were almost normal histologically in four animals of group B, and one showed alveolar phase rejection. In all animals of group A severe rejection was observed, and in group C two of five animals showed vascular phase rejection, two latent phase, and one fibrosis. Histologic examination of the bronchial anastomosis in group B showed almost normal bronchial epithelium and slight submucosal infiltration of mononuclear cells. In group A there was desquamation of epithelium and mild to moderate mononuclear cell infiltration. In group C hyperplasia of the epithelium was observed in two animals, an abscess at the site of anastomosis in one, and mild to moderate mononuclear cell infiltration in all five. With use of laser Doppler velocimetry, bronchial blood flow in group B was found to be the same as in group C. Laser Doppler velocimetry values reached preoperative levels by the twenty-eighth postoperative day in both groups. Although diarrhea developed in two dogs of group B, no other significant side effect of FK 506 was seen.     

Studies of the effects of FK506 on renal allografting in the beagle dog

The immunosuppressive activities of a newly discovered macrolide extracted from Streptomyces tsukubaensis, FK506, were examined using 38 renal allografts in the beagle dog. The median survival time was 15.5 days in dogs without treatment, 61 days with a dose of 0.08 mg/kg/day and 176 days with a dose of 0.16 mg/kg/day of intramuscularly administered FK506. Prolongation of survival was statistically significant when compared with controls (P = 0.02, 0.0044, respectively). None of 6 recipient dogs receiving the agent at a dose of 0.16 mg/kg/day encountered rejection during the treatment course. Three of them survived over 200 days. Oral administration of FK506 at a dose of 0.32 mg/kg/day did not prolong the median survival time (20.5 days) compared with the placebo treated control (16.5 days), but oral treatment with 1.0 mg/kg/day resulted in all of the recipient dogs surviving over 130 days. Histological studies of 7 kidney graft biopsy specimens of the dogs surviving over 3 months revealed no cell infiltration or only some degree of reversible interstitial cell infiltration, but vascular and glomerular changes were not observed in any of the specimens. Irregularity of nuclear shape and cytoplasmic vacuolation of the pars recta of the proximal tubules were observed in one dog each. Liver biopsy specimens showed no consistent evidence of hepatocellular damage. Three dogs died of intussusception 2-3 weeks posttransplant. The dogs treated intramuscularly with 0.32 mg/kg/day suffered from anorexia. Two dogs receiving oral treatment at a dose of 1.0 mg/kg developed papilloma of the skin around day 60, but the tumors disappeared by day 120. We conclude that FK506 is a powerful immunosuppressant in the dog with tolerable side effects.     

Dose study of the immunosuppression of FK 506 in canine lung allo-transplantation

The immunosuppressive effect of FK506 (FK) in comparison to cyclosporine A (CsA) on lung graft rejection was demonstrated using 24 mongrel dogs with left lung allotransplanatation. The cytotoxic activity of peripheral blood mononuclear cells was evaluated using donor skin fibroblasts. In eight dogs not given immunosuppression, the grafted lungs lost aeration 5–10 days postoperatively, and histologic findings revealed grade II rejection and cytotoxic activity elevated to between 10.7 and 60.5%, being an average of 31.2% at an effector/target (E/T) ratio of 50. Of 12 dogs treated with FK, none demonstrated a cytotoxic activity of 10% or more at an E/T ratio of 50. Moreover, histologic examinations of the specimens obtained by open chest biopy revealed no signs of rejection during the first 10 postoperative days of FK administration, except in one dog showing grade I rejection from the FK 0.05 mg/kg group. A dose study of the duration until the onset of graft rejection and the elevation of cytotoxic activity after the termination of FK administration revealed approximately 1–2 weeks in the FK 0.05 mg/kg group, 3–4 weeks in the 0.1 mg/kg group, and later in the 0.4 mg/kg and 2.0 mg/kg groups. However, severe body weight loss was seen in the 0.4 mg/kg and 2.0 mg/kg groups postoperatively, without recovery even after the termination of FK. In fact, two dogs died of pneumonia possibly derived from general emaciation. These results suggest the optimal concentration of FK in canine lung allo-transplantation to be 0.1 mg/kg intramuscularly.     

Optimal serum trough levels of FK506 in renal allotransplantation of the beagle dog

The present study was performed to estimate the optimal serum trough levels of FK506 (FK) for prophylactic use and for the treatment of acute rejection in renal allotransplantation of the beagle dog. The serum trough levels of an immunosuppressive dose of FK 1.0 mg/kg p.o. ranged from 0.1 to 0.4 ng/ml. The data indicate that the effective serum trough level is about 100 times lower than that of cyclosporine, as was already observed in previous in vitro studies. Combining treatment with a nonimmunosuppressive dose of cyclosporine of 2.5 mg/kg could lower the effective trough levels of FK. By the combining treatment, 2 out of 5 renal recipient dogs survived with well-functioning grafts as long as 60 days with the trough levels between 0.04 and 0.07 ng/ml. High-dose 5-day i.m. FK treatment of 0.5 or 1.0 mg/kg was effective in the reversal of acute rejection, with peak serum trough levels during successful rejection therapy ranging between 0.28 and 3.7 ng/ml. Two dogs died of malaise or pneumonia with peak trough levels of 2.25 and 2.78 ng/ml. Among the wide range of the effective trough levels for successful acute rejection therapy, those above 2.0 ng/ml seem to be toxic in some renal-transplanted dogs.     

Immunosuppression with a combination of pg490-88 and a subtherapeutic dose of FK506 in a canine renal allograft model

BACKGROUND: PG490-88 is a water soluble, semisynthetic derivative of a novel compound PG490 (triptolide) purified from the Chinese herb Tripterygium Wilfordii Hook F. In this study, we evaluated the immunosuppressive effect of PG490-88 alone or combined with FK506 in a dog renal transplantation model. METHODS: Recipient and donor male beagle dogs were obtained from different breeders to ensure MHC mismatching. PG490-88 and/or FK506 were administered orally based on protocol design. RESULTS: All dogs in the untreated group developed acute vascular rejection with a median survival time of 6 days. The grafts from this group presented with massive hemorrhage, IgM, IgG, and C4c deposition. Administration of PG490-88 0.06 mg/kg/day significantly prolonged graft survival to a median survival time of 11 days (P=0.038, vs. control). Treatment with FK506 0.3 mg/kg/day did not prolong graft survival with a median survival time of 9 days. Although FK506 0.6 mg/kg/day significantly prolonged survival, this dose was not tolerated by the dogs. The combination of PG 0.06 mg/kg/day and FK506 0.3 mg/kg/day significantly prolonged survival to a median survival time of 15 days (P=0.017, vs. control). Compared to the untreated control group, the pattern of acute humoral rejection was attenuated in renal allografts treated with PG490-88 and/or FK506. C4c deposition was significantly decreased in renal allografts treated with PG490-88 monotherapy and combination therapy. CONCLUSIONS: PG490-88 alone and combined with low dose FK506 significantly prolonged renal allograft survival in a dog model. This agent attenuated acute humoral rejection by inhibiting complement activation and T-cell infiltration.     

Effects of combination treatment with FK506 and cyclosporine on survival time and vascular changes in renal-allograft-recipient dogs

In our previous experiments studying the effects of FK506 on renal allografting in the dog, we encountered two major problems. One problem was anorexia and the other problem was vascular changes mainly in the recipient heart. Anorexia was generally dose dependent, but the vascular changes were seen to be more prominent at lower doses rather than at higher immunosuppressive doses. The present study was undertaken to study these two problems. A nonanorexic, vascular change-related, nonimmunosuppressive dose of FK506 was combined with a low dose of cyclosporine or prednisolone in beagle dogs after renal allografting. Treatment with either FK506 alone at a dose of 0.32 mg/kg or cyclosporine alone at 2.5 mg/kg was not effective in prolonging renal recipient survival. The recipient dogs died of rejection, and a variety of vascular changes were observed in the hearts of both groups. Combined treatment with FK506 and cyclosporine at these same doses resulted in statistically significant prolongation of the survival time of the renal recipient (P less than 0.01), and histologic studies showed that the frequency and severity of the vascular changes were suppressed in the recipient receiving the combined treatment. The combination of FK506 and prednisolone at 0.5 mg/kg was not effective in prolonging survival. Furthermore, the extent of vascular changes was similar to those found in recipients receiving FK506 alone. The data suggest that combined treatment with low doses of both FK506 and cyclosporine acted synergistically in prolonging canine renal allografts and that the vascular changes frequently seen at low doses of FK506 were reduced by additional immunosuppression with a low dose of cyclosporine.     

Immunosuppression with a combination of the leflunomide analog,FK778, and microemulsified cyclosporine for renal transplantation in mongrel dogs

BACKGROUND: The leflunomide analog, FK778, is a selective pyrimidine synthesis inhibitor. In rodent models, FK778 is efficacious in the prevention of allograft and xenograft rejection, and a combination of FK778 and cyclosporine has synergistic immunosuppressive efficacy. METHODS: Heterotopic renal transplantation was performed in 20 dogs. Dogs were randomly assigned to three treatment groups: Neoral alone (n=6), FK778 alone (n=7), or a combination of Neoral and FK778 (n=7). Dogs were killed when the plasma creatinine concentration exceeded 7 mg/dL. A complete postmortem examination was performed and the type of acute-active allograft rejection described. RESULTS: A combination of Neoral and FK778 significantly prolonged allograft survival (P=0.0007), with median survival times of 14.5 days for Neoral alone, 7 days for FK778 alone, and 36 days for Neoral and FK778. Allograft histologic changes were consistent with acute-active allograft rejection in 19 of 20 dogs: in the Neoral-alone group, four dogs were type IB, and two were type IIA; in the FK778-alone group, five dogs were type IB, and one was type IIB; and in the Neoral and FK778 group, three dogs were type IB, three were IIA, and one dog was type III. The dog with type III rejection appeared to experience acute sepsis before rejection. Vomiting, diarrhea, and histologic gastritis and enteritis were commonly observed in dogs treated with the combination of Neoral and FK778. CONCLUSIONS: A combination of Neoral and FK778 prolonged allograft survival in a robust rejection model. Further investigation of FK778 in organ transplantation is warranted.     

Immunosuppression of canine, monkey, and baboon allografts by FK 506: with special reference to synergism with other drugs and to tolerance induction

In dogs the most effective oral dose of FK 506 for prevention of renal homograft rejection was 1.5 mg/kg/day. With maximum credit allowed at 90 days, survival was increased to 61.0 +/- 33.6 (SD) days compared with 13.0 +/- 4.1 in untreated control animals. Higher doses were toxic. The smallest dose that was used (0.5 mg/kg/day) prolonged survival after renal transplantation to 33.7 +/- 23.9 (SD) days. When the small dose of FK 506 was combined with 5 mg/kg/day of cyclosporine and 5 mg of prednisone, five of six canine kidney recipients lived for 90 days. These results were degraded by omission of any of the constituent drugs or reduction by half of the triple drug doses. Thirteen of the dogs treated with various drug regimens lived for 90 days, after which time treatment was stopped; 10 of the dogs eventually rejected the grafts, but three had continued graft function for 6 months or longer and may be permanently tolerant. Moreover, in dogs when 1 mg/kg of intramuscular FK was given to 19 kidney and seven liver recipients for 3 days on postoperative days 1 to 3, 4 to 6, or 7 to 9, the animals survived subsequently for 11 to more than 160 days. All but four of the grafts were eventually rejected, but the prolonged effect of a short course of delayed therapy suggests the possibility of tolerance induction. In cynomolgus monkeys and baboons, FK as a single drug was found to be immunosuppressive after kidney transplantation. Correlation in the dogs and primates between immunosuppression, toxicity, and FK blood levels was not possible because of presently imperfect standardization of assay and monitoring techniques. FK had serious side effects in dogs, but not so obviously in monkeys and not at all in baboons.     

Gemcitabine with cyclosporine or with tacrolimus exerts a synergistic effect and induces tolerance in the rat

BACKGROUND: This study investigated the effect of the antineoplastic agent gemcitabine (dFdC) in combination with cyclosporine (CsA) or with FK506 on acute heart allograft rejection in a rat model. METHODS: Transplantations were performed in the fully allogeneic Lewis-to-Brown Norway strain combination. dFdC, CsA, and FK506 single-drug therapy and combinations of dFdC with CsA and FK506 were administered at various dosages starting on day 1 to prevent and on day 4 to treat acute rejection until day 20. Animals who did not reject their graft were intraperitoneally injected with 108 splenic donor-type lymphocytes. In addition, Lewis and third-party skin grafts were transplanted to these animals. RESULTS: Mean graft survival times under CsA, FK506, and dFdC monotherapy were 18.3/63.7 days (1 mg/5 mg per kg), 41.7 days, and 24.7/38.7 days (100 microg/150 microg per kg), respectively. CsA and FK506 in combination with dFdC prolonged graft survival to more than 100 days (CsA) and more than 95.2 days (FK506). Graft survival after treatment of an ongoing rejection was 21.5/38.3 days for CsA (1 mg/5 mg per kg) and 17.7/59.2 days for dFdC (100 microg/150 microg per kg). The combination of CsA+dFdC prompted indefinite survival of five of six hearts. Lymphocyte inoculation did not induce graft rejection. Notably, none of the Lewis, but all third-party, skin grafts were rejected immediately. Histomorphologic analysis of grafted hearts, however, demonstrated typical features of chronic rejection. CONCLUSIONS: The combination of CsA and FK506 with low-dose dFdC exerts a synergistic effect in the prevention and treatment of acute allograft rejection in this model. Although chronic rejection could not be prevented, strain-specific tolerance was achieved. Therefore, combining standard immunosuppressants with dFdC is a novel, promising strategy for prevention and treatment of acute allograft rejection.     

Short-course immunosuppression using FK506 for rat tracheal allografts

BACKGROUND: A minimizing immunosuppression after a tracheal allotransplantation is desirable. METHODS: We examined the usefulness of a short-course of immunosuppression after tracheal allotransplantation in rat. Each transplant consisting of a 5-ring segment was heterotopically implanted into the omentum. Four animals underwent a syngeneic transplantation and thus served as controls (Group A). Thirty animals underwent an allogeneic transplantation and were randomly classified into 4 groups as follows: No immunosuppression (Group B, n=6), treatment with 0.5 mg/kg of Tacrolims (FK506) (Group C, n=8), 1.0 mg/kg of FK506 (Group D, n=8), and 1.5 mg/kg of FK506 (Group E, n=8). Different doses of FK506 were administered intramuscularly for only three consecutive days after heterotopic tracheal allotransplantation. The serum levels of FK506 were then investigated 3, 7, 14, 21, and 28 days after transplantation in groups C, D, and E. All rats were killed 28 days after transplantation and then the implanted tracheae were harvested, and evaluated histologically. RESULTS: All animals survived for the protocol period. The graft morphology of Group E was significantly better than that of groups B, C, and D regarding both macro- and microscopy, and also showed the same findings as that of Group A, except for low-grade mononuclear cell infiltration. Only in Group E, the FK506 blood level was maintained at over 0.5 ng/ml, which is the lowest detectable limit in this assay, until 21 days after transplantation. CONCLUSIONS: We thus conclude that 1.5 mg/kg of FK506 which was administered for only three consecutive days after surgery may be used to maintain the morphology of tracheal allografts in rats for 28 days after transplantation.     

FK778 controls acute rejection after rat liver allotransplantation showing positive interaction with FK506

This study including prevention and rescue experiments was performed to examine the efficacy of FK778 and its interactions with FK506. In the prevention experiment, Brown-Norway rats transplanted with a 7 Lewis livers received day-course of FK778 or a combination of FK778 and FK506 treatment. For the rescue experiment, the recipients were additionally treated with FK778 from days 7 to 13. Blood chemistry and histopathological findings were used to examine the host and the graft condition. Donor-specific IgM was measured using enzyme-linked immunosorbent assays. The serum trough level of FK778 was examined by high-performance liquid chromatography. FK778 suppressed acute rejection in a dose-dependent manner. The optimal FK778 dosage was 20 mg/kg body weight (BW) d. FK778 treatment from days 7 to 13 rescued liver grafts from ongoing rejection. The combination of FK506 (0.125 mg/kg BW/d) and FK778 (20 mg/kg BW/d) maintained better graft condition than FK778 (20 mg/kg BW/d) monotherapy. In conclusion, FK778 prevents acute rejection in and rescues transplant recipients from ongoing rejection after rat liver transplantation. The optimal monotherapy dosage of FK778 was 20 mg/kg BW/d. Combination therapy with FK506 was more beneficial than FK778 monotherapy.     

Experimental tracheal reconstruction by allotransplantation

Reconstruction using allotransplantation was successfully performed for large defects of the trachea. The defects of ten tracheal rings were surgically created in 28 mongrel dogs and they were repaired with allografts of 5 rings, using over-and-over continuous suture technique with 4-0 Prolene. After the completion of anastomosis, omental pedicle was used to wrap the allograft including both the ends of the graft. Immunosuppressant FR900506 (FK506) was daily administered with a dose of 0.1 mg/kg body weight intramuscularly. When the dogs were sacrificed or succumbed, all the grafts were excised and were examined microscopically and scanning electron microscopically. In some of them, the revascularization from the omental pedicle was examined by infusion of Indian ink from the feeding artery. Eleven dogs survived for more than 30 days and 3 of them did over 120 days. The longest survival is 202 days and the dog is now alive. Twenty out of the 28 allografts were proved to be viable with normal tracheal structure and also free of granulation or stricture. One dog died of perforation of the graft due to rejection. Another dog succumbed from other disease, but the graft was necrotized without the sign of rejection. The viability of the grafts of the remaining 6 dogs were not determined, because the survival time were not long enough, although the grafts were intact macroscopically and microscopically. Three or four weeks after transplantation, the surface of the graft was covered with ciliated epithelium and the tracheal architects were almost normalized. It was proved that revascularization of the tracheal graft from the omental pedicle was established within 7 days following the operation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Drug delivery system using microspheres that contain tacrolimus in porcine small bowel transplantation

Abstract Rejection remains a major barrier to successful bowel transplantation, in spite of improved immunosuppressive techniques. Therefore, new, more effective, immunosuppressants, with fewer side effects, are needed. Biodegradable microspheres containing tacrolimus (FK506) were used in an experimental porcine small bowel transplantation. Twenty pigs underwent transplantation and were divided into four groups according to the immunosuppressive regimen. Group A (n = 5): no immunosuppression; group B (n = 6): 0.2 mg/kg per day of FK506; group C (n = 3): 1.0 mg/kg per day of FK506; group D (n = 6): 0.04 mg/kg per day of FK506 contained in biodegradable microspheres. Rejection was diagnosed macroscopically by endoscopic examination and histologically by biopsy specimen analysis. The mean survival time and standard deviation (SD) were 8.8±3.5, 11.0±1.4, 9.7±2.5 and 28.6 ±22.5 days for groups A, B, C, and D, respectively, with a statistically significant difference found between group D, on the one hand, and groups A, B and C, on the other. The mean trough blood concentration of FK506 was 10.5 ±2.2, 27.9 ±6.0 and 10.5 ±3.5 ng/ml in groups B, C and D, respectively. In groups A and B, all pigs died of rejection, without infection. In group C, all died of infection, without rejection. In contrast, none of the pigs in group D developed rejection or infection. Our results clearly show that the drug delivery system using biodegradable micro-spheres that contain FK506 is effective for controlling rejection with fewer side effects in the porcine small bowel transplantation.     

Drug delivery system using microspheres that contain tacrolimus in porcine small bowel transplantation

Rejection remains a major barrier to successful bowel transplantation, in spite of improved immunosuppressive techniques. Therefore, new, more effective, immunosuppressants, with fewer side effects, are needed. Biodegradable microspheres containing tacrolimus (FK506) were used in an experimental porcine small bowel transplantation. Twenty pigs underwent transplantation and were divided into four groups according to the immunosuppressive regimen. Group A (n=5): no immunosuppression; group B (n=6): 0.2 mg/kg per day of FK506; group C (n=3): 1.0 mg/kg per day of FK506; group D (n=6): 0.04 mg/kg per day of FK506 contained in biodegradable microspheres. Rejection was diagnosed macroscopically by endoscopic examination and histologically by biopsy specimen analysis. The mean survival time and standard deviation (SD) were 8.8±3.5, 11.0±1.4, 9.7±2.5 and 28.6±22.5 days for groups A, B, C, and D, respectively, with a statistically significant difference found between group D, on the one hand, and groups A, B and C, on the other. The mean trough blood concentration of FK506 was 10.5±2.2, 27.9±6.0 and 10.5±3.5 ng/ml in groups B, C and D, respectively. In groups A and B, all pigs died of rejection, without infection. In group C, all died of infection, without rejection. In contrast, none of the pigs in group D developed rejection or infection. Our results clearly show that the drug delivery system using biodegradable microspheres that contain FK506 is effective for controlling rejection with fewer side effects in the porcine small bowel transplantation.     

两种包含他克莫司的免疫抑制方案在肾移植中的应用体会

目的　探讨适合中国人的他克莫司 (FK50 6)剂量。方法　对 8例使用高剂量FK50 6(0 .2mg·kg- 1 ·d- 1 )方案肾移植受者 (A组 )及 34例使用低剂量FK50 6(0 .1mg·kg- 1 ·d- 1 )受者 (B组 )术后早期血肌酐、排斥反应发生率及免疫抑制剂的不良反应进行比较。结果　A、B两组术后 2个月血肌酐水平的差异无显著性 (P >0 .0 5) ;A组半年内未见急性排斥反应发生 ;B组有 1例因血中FK50 6的浓度偏低而发生急性排斥反应 ,2例肾组织活检提示肾小管炎 ;两个组在随访期内均未见严重感染发生 ;药物的不良反应B组较少、较轻。结论　应用低剂量FK50 6组成的免疫抑制方案 ,在降低药物毒副作用的同时 ,并不影响其疗效     

RS-61443 reverses acute allograft rejection in dogs

RS-61443, a morpholinoethyl ester of mycophenolic acid, has been shown to prevent renal allograft rejection in dogs when administered in combination with low-dose cyclosporine and prednisolone. The purpose of this study was to test whether high-dose RS-61443 can reverse acute renal allograft rejection. Mongrel dogs receiving a renal allograft were treated with baseline immunosuppression consisting of RS-61443 10 mg/kg, cyclosporine 5 mg/kg, and prednisolone 0.1 mg/kg. All animals developed acute allograft rejection. Dogs in group I (n = 11) received 14, 7, and 3.5 mg/kg methylprednisolone intravenously on 3 consecutive days after the diagnosis of rejection. Dogs in group II (n = 16) were given RS-61443 80 mg/kg twice daily. After rejection treatment, RS-61443 was increased to 20 mg/kg in all animals; cyclosporine and prednisolone were continued as before. In group I, five of 11 dogs developed uncontrollable rejection; in six of 11 dogs only a temporary reversal occurred. None of the dogs in group I survived for more than 20 days after the diagnosis of rejection. In group II rejection was completely reversed in 14 of 16 dogs (87.5%), resulting in a return of serum creatinine to prerejection levels. Thus, high-dose therapy with RS-61443 can successfully reverse acute kidney allograft rejection in dogs in a high proportion of cases.     

Efficacy of rapamycin and FK 506 in prolonging rat hind limb allograft survival.

OBJECTIVE: Graft rejection and the toxicity of current immunosuppressive regimens preclude the application of microsurgical advances to transplantation of limbs or other nonessential parts. If limb transplantation is to become a clinical reality, newer, safer, more effective immunosuppressive agents are needed. SUMMARY BACKGROUND DATA: Rapamycin (RPM) and FK 506 are fungal macrolide antibiotics with effective immunosuppressive properties demonstrated in several animal models. RPM is more potent and effective than is FK 506 in rat cardiac allografts and has demonstrated synergy with cyclosporine (CsA) in limb allograft models. METHODS: An orthotopic rat hind limb allograft model (Brown-Norway [RT-1n] to Lewis [RT-1(1)] rats was used. RPM (doses, 3.0, 4.5, and 6.0 mg/kg/day) was administered intraperitoneally on postoperative days 1 to 14. FK 506 (6 mg/kg/day) was administered orally on postoperative 1 to 14 and 1 to 90 and at rejection onset (10 mg/kg/day for salvage). CsA with RPM (postoperative days 1 to 14) was used to assess synergy, with CsA alone serving as the control. Other controls included untreated and placebo-treated allografted animals. The permutation test and Mann-Whitney test were applied to the data. RESULTS: The mean survival times were assessed as follows: (1) control (placebo, untreated), 5 days; (2) RPM groups, 9.5, 10.6, and 8.7 days; (3) 14-day FK 506, 28 days; (4) 90-day FK 506, > 90 days; (5) CsA, 17.3 days; and (6) CsA with RPM, 19.3 days. FK 506 significantly prolonged graft survival compared with RPM (Permutation Test, p < 0.001 and Mann-Whitney Test, p < 0.05). FK 506 salvage reversed early rejection. High-dose RPM produced significant toxicity. Synergy between CsA and RPM was not demonstrated. CONCLUSIONS: FK 506 prolongs allograft survival, reverses early rejection, and prevents rejection without clinical toxicity when given continually. RPM does not prevent rejection in this model and produces significant toxicity at high doses. FK 506 may be a first step in making limb transplantation a clinical reality in reconstructive surgery.     

A prospective randomized trial comparing the efficacy of tacrolimus versus cyclosporine in black recipients of primary cadaveric renal transplants.

BACKGROUND: We performed a prospective randomized trial to compare the efficacy and safety of tacrolimus (FK506) versus cyclosporine (CSA) in black primary cadaveric renal transplant (CRT) recipients. METHODS: Between December 1994 and February 1997, 35 black primary CRT recipients were enrolled in this trial. All patients received 7 days of induction therapy with OKT3. Fourteen patients received FK506 and prednisone only. Twenty-one patients received CSA, azathioprine, and prednisone. The two groups were comparable in terms of age, gender, plasma renin activity, human leukocyte antigen mismatches, and cause of renal failure. RESULTS: Patient and graft survival were 12 of 14 (86%) for the FK506 group and 20 of 21 (95%) for the CSA group (P = 0.71). Three patients died owing to cardiac events with functioning grafts. Acute rejection was 2 of 14 (14%) for the FK506 and 8 of 21 (38%) for the CSA group (P = 0.25). Two other patients on CSA were converted to FK506 as rescue for OKT3-resistant rejection. Mean serum cholesterol at 1 year was 198 +/- 45 mg/dL for the FK506 group and 244 +/- 49 mg/dL for the CSA group (P = 0.03). Mean serum creatinine at 1 year was 1.39 +/- 0.38 mg/dL for the FK506 group and 1.94 +/- 0.64 mg/dL for the CSA group (P = 0.02). CONCLUSION: Patient and graft survival were similar in both groups at 1 year posttransplant. Although statistically not significant, the incidence of acute rejection was lower in the FK506 group. Furthermore, FK506-treated patients had significantly lower serum creatinine and cholesterol levels at 1 year posttransplant.     

Donor leukocytes combined with delayed immunosupressive drug therapy prolong limb allograft survival

Donor leukocytes administered at the time of transplantation may prolong organ allograft survival. Delayed administration of calcineurin inhibitors, such as FK506 or cyclosporine, may enhance their efficacy. Herein the effectiveness of this strategy to promote limb transplant survival was investigated in the strong histocompatibility barrier of Brown-Norway donor to Lewis recipients. Donor leukocytes (6 x 10(7) intravenously) were injected on the day of transplantation followed on day 1 to 14 with mycophenolate mofetil (MMF; 15 mg/kg/d) and prednisone, (0.5 mg/kg/d) which were then tapered by 20% each week and stopped at week 7. Administration of of FK506 (2 mg/kg/d) was started on day 4 and continued for 8 weeks, then tapered for 4 weeks to a maintenance dose of 0.8 mg/kg/d, which was continued for 12 weeks (group A; n = 8). A control group (n = 8) underwent identical treatment save for donor leukocyte injection but rather commencement of FK506 on day 1. Rejection was common during FK506 tapering in both groups. However group A showed a significantly later onset, a shorter period for reversal of the first rejection, and a significantly lower dosage of FK506 at the time of rejection. After the completion of immunosuppression, rejection occurred significantly later in group A than the control group with one animal surviving without immunosuppression on day 344. This is the first trial of a donor leukocyte injection combined with delayed FK506 administration in limb transplantation, which suggested that it could produce a modest but significant improvement in outcome.     

Immunosuppression with FK506 in rat arterial allografts: fate of allogeneic endothelial cells

PURPOSE: This study clarified the efficacy of low-dose FK506 and the possibility of discontinuing the use of FK506. METHODS: Fresh carotid arteries were allografted from ACI rats to Lewis rats. FK506 (0.2 mg/kg/day) was given intramuscularly from day 3 after transplantation until the rats were killed (group III), or it was given for 4 weeks and then discontinued (group IV). Isogeneic (group I) and allogeneic (group II) models served as untreated control groups. Grafts were harvested on days 0, 1, 3, 7, 14, 21, 28, 70, and 105 after transplantation. Histological evaluation and measurement of the endothelial cell (EC)-covered area were performed by means of scanning electron microscopy. RESULTS: In group I, ECs were denuded immediately after transplantation and subsequently regenerated within 2 weeks. In group II, after denudation and regeneration of ECs, massive leukocyte adhesion and subsequent destruction of regenerated ECs, followed by intimal hyperplasia, were observed. In group III, FK506 suppressed rejection almost completely, without intimal hyperplasia. In group IV, severe rejection and denudation of regenerated intima appeared 2 weeks after the use of FK506 ended. CONCLUSION: The denudation and regeneration of ECs may play an important role in the process of rejection and graft performance. FK506 proved to be successful in rat arterial allografting, and ECs of donor origin could survive on the allograft as long as FK506 was effective; however, cessation of the use of FK506 resulted in severe destruction of intima. To prevent allograft failure, long-term administration of an immunosuppressant is essential.