The duration of administration of monoclonal antibody OKT3 for induction immunosuppression after heart transplantation

The effective treatment of refractory allograft rejection with murine antihuman monoclonal antibody muromonab-CD3 (OKT3) and of patients with renal dysfunction has led to its use as induction therapy. The optimal protocol for OKT3 prophylaxis remains to be established. We compared 59 patients consecutively transplanted with the total orthotopic technique between 1/92 and 5/94. The first 21 patients were treated with OKT3 for 14 days, the next 19 for 10 days, and the last 19 for 7 days. Patients operated with different surgical techniques or other induction treatment were excluded. We compared length of stay (total and ICU), time to first rejection, rejection incidence and infection incidence (cytomegalovirus separately), and survival. Preoperative characteristics were similar except for significantly younger age in the 10-day group (p = 0.04). Preoperative hemodynamic parameters were similar except for a significantly higher left-ventricular ejection fraction (21%) in the 7-day group. Length of stays in the ICU and hospital were similar for the three groups (p = NS). Freedom from cellular rejection was lower with the 7 days course (p = 0.02), but freedom from humoral rejection was slightly higher (p = 0.11). However, patients in the 7-day group required treatment for rejection less frequently than patients in the other two groups (95% untreated at 2 months vs. 43% in the 14-day and 53% in the 10-day group; p = 0.002). There were no differences in incidence of infections, including cytomegalovirus. Survival was similar between the groups. There was one death in the 14-day and 1 in the 10-day group, both due to rejection. In conclusion, OKT3 therapy can be reduced safely to 7 days with a higher overall incidence of rejection but no increased necessity to treat for rejection, and no difference in infection incidence.

Tacrolimus: a superior agent to OKT3 for treating cases of persistent rejection after intrathoracic transplantation

Acute myocardial rejection refractory to treatment still contributes significantly to patient death after intrathoracic transplantation. A historical series of 25 patients who received OKT3 (5 mg/day for 10 days) was compared with our current experience with 14 patients treated with tacrolimus (0.1 mg/kg/day targeting whole blood concentrations of 13 to 18 ng/ml): all 39 patients having persistent rejection unresponsive to treatment at the time of conversion. Mean periods of follow-up were 842.9 days and 342.6 days, respectively. Actuarial 1-year patient survival rates were 64.0% and 76.2% for the OKT3 and tacrolimus treatment groups, with most of the deaths in the OKT3 group occurring early (p = 0.064). Causes of death for patients receiving OKT3 included acute rejection (n = 5), infection (n = 3), carcinoma (n = 2), multiorgan failure (n = 1) and graft vessel disease (n = 1). The two deaths in the tacrolimus treatment group were the result of infections. Eighty percent of patients treated with OKT3 subsequently experienced further rejection episodes, in many cases necessitating methotrexate therapy. In contrast, only one patient (7.1%) from the tacrolimus group was diagnosed with rejection after conversion (p < 0.001). In conclusion, when compared with OKT3 therapy, a switch in baseline immunosuppression from cyclosporine to tacrolimus seems to be markedly more effective, as well as being safe for the treatment of persistent acute rejection.

Treatment of steroid-resistant and recurrent acute cardiac transplant rejection with a short course of antibody therapy

The purpose of this study was to assess the efficacy of short courses of OKT3 and ATG, respectively, for steroid resistant or recurrent acute allograft cardiac rejection (AR). Between June 1988 and March 1994, 101 heart transplant patients were treated with a quadruple sequential immunosuppression protocol (ATG, azathioprine, CsA, and prednisone). AR was diagnosed by endomyocardial biopsy (EMB), and patients with scores > 2 (ISHLT) received pulse methylprednisolone, 500 mg i.v. on 3 consecutive days. In cases of steroid-resistant or recurrent AR, OKT3 (5 mg/d) or ATG (1.5-2.5 mg/kg/d), was administered for 5-7 d instead of the usual 10-14 d course. OKT3 (17 courses; 10 steroid resistant, 7 recurrent AR; 5.3 +/- 0.7 doses) was given to 16 patients (4F/12M, 45 +/- 11 yr), 29-269 d after transplantation. ATG (8 courses; 5 steroid resistant, 3 recurrent AR; 4.9 +/- 0.6 doses) was given to 8 patients (1F/7M, 53 +/- 7 yr), 23-503 d after transplantation. Successful treatment of AR with a score < 2 at the first and second EMB after treatment was 88% and 88% with OKT3, and 87.5% and 100% with ATG, respectively. Throughout follow-up (50 +/- 22 months after OKT3; 49 +/- 28 months after ATG), there was a trend towards lower incidence of subsequent AR after ATG (25% vs. 69%, P = 0.09), and similar incidence of infections, graft atherosclerosis and mortality. No cases of lymphoproliferative disorder were observed. We conclude that short courses of OKT3 or ATG are safe and effective for the treatment of steroid resistant or recurrent AR, with a similar incidence of complications. These results may have cost-effectiveness implications and need to be confirmed in a randomized study.

Cerebral complications of murine monoclonal CD3 antibody (OKT3): CT and MR findings

Treatment of acute renal allograft rejection with mouse monoclonal antibody (OKT3) is associated with systemic and neurologic side effects. We describe cerebral abnormalities in a 13-year-old boy with steroid-resistant renal allograft rejection. After treatment with OKT3, an acute neurologic syndrome developed, including seizures, lethargy, and decreased mental function. CT and MR imaging revealed confluent cerebral lesions at the corticomedullary junction. Contrast-enhanced MR images showed patchy enhancement, indicating blood-brain barrier dysfunction. The diagnosis of OKT3-induced encephalopathy with cerebral edema and capillary leak syndrome was made. Although CT and MR findings are nonspecific, neuroradiologists should be aware of this condition in transplant patients treated with OKT3.

Hematopoietic changes induced by a single injection of anti-CD3 monoclonal antibody into normal mice

The present study evaluates hematopoietic modifications consecutive to in vivo treatment of mice with anti-CD3 monoclonal antibodies (mAb). The hamster mAb 145-2C11, administered in a single i.v. injection of 10 micrograms, induced the release of both interleukin 3 (IL-3) and GM-CSF into the circulation. IL-3 could be detected in the serum within 1 h, attained maximal levels after 4 h and had disappeared after 24 h. Three days later, treated mice exhibited a two- to threefold rise in blood neutrophil levels and increased spleen cell counts. Concomitantly, the incidence of nucleated erythroid cells in these spleens increased around 10-fold, relative to controls having received hamster Ig. At the same time point, clonogenic progenitor frequencies were 10-fold higher in spleens from treated mice than in those from control mice. Furthermore, the responsiveness of these splenocytes to IL-3, in terms of histamine synthesis, was enhanced. In contrast, bone marrow cell populations were only slightly affected by anti-CD3 injection. All hematopoietic changes required multivalent crosslinking of the mAb for induction, since F(ab')2 fragments lacked this activity. A return to normal occurred 7-10 days after treatment. Two i.v. injections of recombinant murine IL-3 together with recombinant murine GM-CSF on a single day had a less pronounced effect on progenitor cell frequencies in the spleen than treatment with anti-CD3. This difference is probably due to the amplification of growth factor-induced hematopoiesis by the interaction with other cytokines generated in response to anti-CD3.

Kaposi's sarcoma in renal-transplant recipients: experience at the Catholic University in Rome, 1988-1996

BACKGROUND

The incidence of Kaposi's sarcoma (KS) in patients transplanted at the Organ Transplant Center of Catholic University in Rome appears to have increased in recent years.

OBJECTIVE

To describe the clinical characteristics of KS in a group of transplant recipients.

METHODS

Over 8 years, a total of 302 renal-transplant recipients were followed. When KS was suspected, histology and staging procedures were performed.

RESULTS

Ten cases of KS have been diagnosed (8 males, 2 females; age 46.4 +/- 9.4 years); 4 of them were on triple therapy. All the patients were HIV-1 seronegative. The onset of KS occurred 3 months to 4 years after transplantation (21.1 +/- 17.6 months). The disease was limited to the skin in 6 cases and involved internal organs in the remaining 4. Four patients experienced complete remission of the disease following reduction of the immunosuppressive therapy.

CONCLUSION

The high incidence of KS in this population (2.98%), as compared to that reported in other transplant patient groups, suggests that, besides viral infection, genetic predisposition may play a pathogenetic role. However, immunosuppression is the leading factor in transplant patients.

Pretransplant malignancy in candidates and posttransplant malignancy in recipients of cardiac transplantation

BACKGROUND

Malignancy is generally considered a contraindication for cardiac transplantation, whereas secondary malignancy has been described under chronic immunosuppression.

PATIENTS AND METHODS

We report here the frequency of malignancy encountered among the 495 patients evaluated at our cardiac transplant centre as well as the incidence and the course of post-transplant malignancy among 129 consecutive patients who underwent cardiac-transplantation, with a subsequent minimum follow-up of 6 months.

RESULTS

A total of 10 out of 495 patients (2%) evaluated for heart transplantation presented with a history of previous malignancy: 3 of them underwent transplantation (2 survive, 1 died) whereas in the remaining 7 patients neoplasia was considered a contraindication for cardiac transplantation, and all 7 died (4 cardiac, 3 tumor-related deaths). Post-transplant malignancy was diagnosed in 10 of 129 patients (9%) 35 +/- 15 months after transplantation (6 skin cancers, 1 lymphoproliferative disease, 3 solid tumors). No significant association was found between post-transplant malignancy and primary prophylaxis with antithymocyte globulin (ATG) or murine antihuman T-cell monoclonal antibodies (OKT3).

CONCLUSION

These results confirm that pre-transplant malignancy is not an absolute contraindication for cardiac transplantation and that post-transplant follow-up must include careful monitoring of post-transplant malignancy.

Reduced dose OKT3 prophylaxis in sensitised kidney recipients

Prophylactic use of the monoclonal antibody OKT3 has been studied for the prevention of rejection in sensitised renal transplant recipients. Patients receiving a full dose (FD) regimen were compared to a subsequent consecutive group of patients receiving a reduced dose (RD) regimen. The characteristics of the two groups were not significantly different with regard to age, HLA mismatch and panel-reactive antibody (PRA) status. The number of days that OKT3 was given was 12.9 +/- 1.8 for the FD regimen and 11.3 +/- 2.8 for the RD regimen. The total dose of OKT3 given was 64.4 +/- 9 mg (FD) and 38.3 +/- 8.5 mg (RD). Patient survival at 12 months was 8/8 for FD and 17/17 for RD. Graft survival at 12 months was 7/8 for FD and 17/17 for RD. Creatinine at 24 months was 185 +/- 68 and 201 +/- 81 mumol/l for FD and RD, respectively. A reduced dose regimen of OKT3 produced excellent and comparable results to the standard recommended full-dose regimen. The cost per patient was reduced 40% from 5676 pounds for FD to 3344 pounds for RD.

Increased dermal expression of ICAM-1 and VCAM-1 after administration of OKT3 in man

OKT3 induces a systemic release of cytokines and a profound peripheral lymphocytopenia. In vitro, tumor necrosis factor-alpha, interleukin-1, and interferon-gamma increase adhesion molecule expression on vascular endothelium. To investigate the effects of OKT3 induced cytokine release on endothelial- and lymphocyte adhesion molecule expression in vivo, we studied sequential skin biopsies of six renal allograft recipients treated for acute rejection with 5 mg OKT3. An additional group of six patients treated for acute rejection with 50 mg methylprednisolone served as a control group. Compared to pre-treatment biopsies, biopsies taken 4.5- and 24 hours after the first OKT3 dose showed a maximal increase in VCAM-1 and ICAM-1 expression, respectively. In parallel, an increased number of CD2+, CD11a+, and CD49d+ mononuclear cells in the skin was observed in all OKT3 treated patients. No changes were observed after methylprednisolone treatment. We conclude that the OKT3 induced cytokine release induces increased ICAM-1- and VCAM-1 expression on vascular endothelium, leading to increased influx of CD2+ lymphocytes which may contribute to the peripheral lymphocytopenia after OKT3.

OKT3 escalating dose regimens provide effective therapy for renal allograft rejection

Dose-response relationships for anti-CD3 monoclonal antibody (mAb) therapy remain undefined, particularly with respect to higher dose ranges. The clinical efficacy and safety of an OKT3 dosing regimen that incorporates higher doses (escalating dose regimens) was examined in a pilot trial. Patients undergoing acute rejection were treated with a 7-d course of OKT3 in which the daily OKT3 dose was escalated during treatment course (daily doses 5, 5, 5, 5, 10, 15, 25 mg). The total amount of OKT3 given was equal to a standard 14-d course (70 mg). A total of 10 primary cadaveric renal transplant recipients were treated, and data analyzed from a median follow up of 5 months (range 3-13 months). Pre-OKT3 immunosuppressive therapy consisted of ATGAM induction therapy (n = 8), and corticosteroid rejection therapy (n = 6, 18.6 +/- 11.4 mg/kg). Median time of first rejection was 32 d (12-48 d) and median time to OKT3 was 33 d (range 15-42 d). Pre-OKT3 histology (by Banff criteria) included: mild ACR (n = 6), moderate ACR (n = 2), AVR (n = 1), ACR and acute transplant glomerulopathy (n = 1). Rejection reversal rate with escalating dose OKT3 was 100%, and each patient experienced a rapid reversal of rejection (i.e. reversal within 14 d initiation of OKT3 therapy). Six recurrent rejection episodes were diagnosed in 5 patients with a median time to recurrent rejection of 30 d following cessation of OKT3 therapy. All recurrent rejection episodes were successfully treated (FK 506 n = 4, corticosteroids n = 1, and OKT3 n = 1). CMV disease was limited to a single episode of CMV viremia in one patient. PTLD was observed in one patient who had coexisting vascular rejection at the time of PTLD diagnosis. Short- and long-term graft function is excellent (pre-rejection baseline creatinine 1.8 +/- 0.4 mg/dl, current creatinine 1.75 +/- 0.4 mg/dl). Monitoring of OKT3 serum levels revealed that patients maintained therapeutic serum levels for an average of 4 d following the last OKT3 dose. Circulating CD3+ and CD5+ cells were maintained below baseline levels for at least 10 d following the last OKT3 dose. Anti-OKT3 antibody formation occurred in 22% of patients, however, anti-idiotypic responses were of low titer. Adverse reactions experienced during dose escalation were minimal compared to first dose reactions, and consisted primarily of mild headaches and arthralgias in a minority of patients. OKT3 EDR, by obviating monitoring and administration costs, are cost effective [OKT3 EDR $8088, OKT3 SDR (10 d) $9684, OKT3 SDR (14 d) $13,224]. In conclusion, escalating dose regimens of OKT3: 1) provide rejection reversal rates similar to standard dose regimens, 2) provide high OKT3 serum levels and reliable CD3+ cell depletion, 3) induce minimal adverse reactions during dose escalation, and 4) may decrease costs by obviating the need for monitoring peripheral blood T cells and by decreasing administration costs and outpatient visits.

Half dose of OKT3 is efficient in treatment of steroid-resistant renal allograft rejection

Rejection episodes in renal allograft recipients are usually efficiently treated with high doses of intravenous methylprednisolone. Rejection therapy with OKT3 is often reserved for steroid-resistant episodes. However, the optimal dose of OKT3 in the treatment of steroid-resistant rejection is not known. Therefore, we randomized renal transplant recipients with steroid-resistant rejection to treatment with a standard daily intravenous dose of either 5 mg of OKT3 (n=15) or 2.5 mg of OKT3 (n=15) for 10 days. Circulating T cells (measured as CD2+ cells) were adequately and equally depleted in the two groups. Three grafts were lost due to rejection within the first 3 months following OKT3 administration, one in the 2.5 mg OKT3 group and two in the 5 mg OKT3 group. Two nonimmunologic graft losses occurred in the 2.5 mg OKT3 group. Median serum creatinine values were not different between the two groups, neither at the start (median values: 200 micormol/L in the 5 mg OKT3 group vs. 188 micromol/L in the 2.5 mg group) nor immediately after OKT3 rescue therapy (202 micromol/L vs. 185 micromol/L, respectively). Eight cytomegalovirus infections occurred in each group. Two re-rejection episodes occurred in the 5 mg OKT3 group and one occurred in the 2.5 mg OKT3 group. All responded to treatment. Function of the remaining grafts estimated by serum creatinine after a mean long-term follow-up of 18 months (range, 6-36 months) revealed no differences (185 micromol/L in the 5 mg OKT3 group vs. 170 micromol/L in the 2.5 mg OKT3 group). We conclude that OKT3 treatment of steroid-resistant rejections in renal transplant recipients is equally effective in daily doses of 2.5 mg and 5 mg with respect to reversal rate and long-term outcome.

A cost-effectiveness analysis of OKT3 induction therapy in cadaveric kidney transplantation

We evaluated the cost-effectiveness of a standard immunosuppressive regimen versus an OKT3 induction regimen in cadaveric kidney transplant recipients. Cost estimates were based on results from a five-center randomized trial comparing the safety and efficacy of OKT3 induction with a conventional triple-drug regimen and financial data from the National Cooperative Transplantation Study, the Medicare Provider and Analysis Review database, and other sources. Patients received OKT3 (5 mg/day) by intravenous (IV) bolus injection for 10 to 14 consecutive days in conjunction with azathioprine, prednisone, and the delayed addition of cyclosporine (CsA) on day 11 (n = 105) or a conventional immunosuppressive regimen consisting of CsA, azathioprine, and prednisone (n = 102). The following measures were used to evaluate the two regimens: costs incurred between transplantation and graft failure; the effectiveness of the two regimens as defined by length of graft survival; and cost-effectiveness ratios through 5 years of observed follow-up and modeled through the expected duration of graft survival. Results showed that OKT3 induction uniformly adds $8,219 to the cost of the transplant hospitalization. However, most of this cost is offset by a reduction in the cost of treating rejection episodes in the OKT3 group (P = 0.002). A trend toward improved graft survival was detected in the OKT3 group (P = 0.158). Through 5 years of observed follow-up, costs per year of graft survival are $30,474 with OKT3 versus $32,687 with the conventional regimen. Modeled through the expected duration of graft survival, OKT3 induction costs $8,335 for each additional year of graft survival. Results are fairly insensitive to wide variations in baseline assumptions. We conclude that OKT3 induction improves the cost-effectiveness of kidney transplantation.

Antilymphocyte induction immunosuppression in the post-Minnesota anti-lymphocyte globulin era: incidence of renal dysfunction and delayed graft function. A single center experience

Between 4/91 and 12/93, 262 patients received cadaveric (CRT) (n = 205) or living donor (LRT) (non-HLA identical) renal transplants. All patients were treated with the same sequential induction immunosuppression protocol, with the exception of different forms of antilymphocyte sera: either Minnesota antilymphocyte globulin (MALG), antithymocyte globulin (ATG), orthoclone antibody (OKT3), d 1 postoperatively, or OKT3 intraoperatively. With the withdrawal of MALG from the market, we wished to prospectively analyze the influence of these other antilymphocyte therapies on the incidence of delayed graft function (DGF) (the requirement for hemodialysis within the first week postoperatively) and renal function during the first 3 d postoperatively and during the subsequent .6 months post-transplantation and compare that with our MALG experience. Of the 205 CRT, 76 received MALG with a DGF rate of 18.4%, 50 received ATGAM with a DGF rate of 22.0%, 38 received OKT3 postoperatively with a DGF rate of 39.5%, and 41 received OKT3 intraoperatively with a DGF rate of 39%. Of the 57 LRT, only two patients, one receiving intraoperatively OKT3 (secondary to graft thrombosis), and one MALG patient, suffered DGF. Serum creatinine values were obtained from postoperative d 1 through postoperative d 4 for 185 patients. Each of the four groups showed similar mean decrements in serum creatinine. The number of grafts functioning at 1, 2, 3 and 6 months postoperatively and serum creatinine values were not statistically different between the groups. We conclude that induction immunosuppression with MALG and ATGAM is associated with a lower DGF rate than OKT3 given either intraoperatively or postoperatively. However, with 6 months of follow-up, we do not observe any difference in the incidence of rejection or graft function between the therapies. Consequently, we have chosen ATGAM as our preferred inductive therapy in the absence of MALG owing to its lower associated DGF rate.

Bispecific antibody-mediated immunotherapy of the BCL1 lymphoma: increased efficacy with multiple injections and CD28-induced costimulation

The BCL1 lymphoma in Balb/c mice can be successfully treated with bispecific (anti-CD3 x anti-idiotype) antibodies (BSABs). In these experiments, animals were injected intraperitoneally (IP) with 5 x 10(3) tumor cells (day 0) and treated with one single intravenous (IV) injection of 5 micrograms BSAB (day 9). Because cross-linking of the CD3 complex is not in itself sufficient to activate resting T cells, the therapeutic success was mainly based on the progressive retargeting of the relatively small cytotoxic T-lymphocyte effector cell pool already in existence in vivo. For this reason, the therapy lost its effectiveness at higher tumor loads. Two possibilities were explored to treat mice with a higher tumor load (10(5) tumor cells). First multiple injections of BSABs were used, but a dose-related monovalent anti-CD3 immunosuppression was induced. This approach was only beneficial when the immune system was able to recover from the previous injection of BSAB. As a second approach, CD28 costimulation together with BSABs were used in an attempt to activate resting T cells, ultimately enlarging the effector T-cell pool. However, we were repeatedly unsuccessful in attempts to improve our in vivo results using young, naive animals in which the majority of T cells are of the naive phenotype. Only when animals were primed to induce the memory T-cell type was a significantly better outcome observed, and then only with multiple injections of BSABs and anti-CD28 monoclonal antibodies (MoAbs), rather than with BSAB or anti-CD28 MoAb alone. These results suggest that this combination was able to activate memory and effector T cells and to focus them on the tumor, but was unable to activate naive T cells fully. The in vivo potency of the BSAB and CD28 costimulation was shown by the fact that one-tenth of the quantity of BSAB was required to cure animals with 20 times the tumor load.

How best to use tacrolimus (FK506) for treatment of steroid- and OKT3-resistant rejection after renal transplantation

Nineteen patients with biopsy-confirmed ongoing acute rejection of renal allografts were converted from standard immunosuppression to FK506. Eight grafts showed vascular rejection and 11 had cellular rejection on biopsy. All patients had already received intravenous high-dose steroid treatment. Ten patients also had additional OKT3 rescue therapy. Initial FK506 doses were 0.13 +/- 0.06 mg/kg/day; the FK506 whole blood trough level after 3 days of treatment was 9.3 +/- 4.5 ng/ml. After conversion to FK506 all but four patients also received azathioprine, 1.5-2 mg/kg/day, and all patients received oral prednisolone. Concomitant with initiation of FK506, an anti-infective prophylaxis was prescribed, consisting of ganciclovir and trimethoprim/sulfamethoxazole. Sixteen out of 19 of the grafts (84%) were rescued successfully, including two grafts of patients already on hemodialysis at the time of conversion. Graft function of the responders improved from an average serum creatinine level of 364 +/- 109 mumol/L to 154 +/- 49 mumol/L. Of the patients receiving high-dose steroids alone prior to FK506 initiation, 8/9 responded to FK506 treatment, compared with 8/10 of those who had also received OKT3. During the mean follow-up of 35 weeks after conversion, no clinically apparent cytomegalovirus infection and no pneumonia were seen. Treatment with FK506 may successfully suppress ongoing acute rejection, even if antilymphocyte preparations have failed. FK506 can be used at a lower dose than so far recommended without impairing the antirejection potential. An additional anti-infective prophylaxis seems effective in preventing severe complications in the first months after rejection therapy.

Kaposi's sarcoma after liver transplantation

BACKGROUND

Kaposi's sarcoma (KS), is a known complication following kidney transplantation. It has been reported more rarely following liver transplantation.

OBJECTIVE

To assess the clinico-epidemiologic data of KS after liver transplantation.

METHODS

150 liver graft recipients were examined; those presenting with KS were studied clinically, histologically and virologically.

RESULTS

Three cases of KS were observed. The three patients had been treated with OKT3 antiserum in addition to the standard regimen. The delay of appearance varied from 5 to 36 months. Two patients had a few cutaneous lesions and 1 had more extensive involvement; none of them had visceral localizations. In 2 cases, herpesvirus-like DNA sequences were detected within the lesions. Therapy consisted in decreasing the immunosuppressive treatment, in association with alpha-interferon or vindesine in 2 cases, respectively. All patients were alive after a follow-up of 19-45 months.

CONCLUSION

KS seems relatively frequent (2%) and appears within a short delay after liver transplantation; the prognosis may be more favourable than previously reported.

Efficacy of rejection prophylaxis with OKT3 in renal transplantation. Collaborative Transplant Study

The results of renal cadaver transplants performed between 1984 and 1994 and reported to the Collaborative Transplant Study were analyzed to examine the effect of rejection prophylaxis with OKT3. OKT3 prophylaxis with sequential (i.e., delayed) addition of cyclosporine (CsA), compared with immunosuppressive treatment that included CsA but not OKT3, resulted in a significantly higher overall 3-year graft survival rate in recipients of first transplants (75 +/- 1% vs. 71 +/- 1%, respectively; P < 0.0001) and in recipients of retransplants (68 +/- 2% vs. 62 +/- 1%, respectively; P < 0.001). In contrast, the simultaneous administration of OKT3 and CsA from the first posttransplant day did not result in improved graft survival over treatment with CsA alone. Graft survival rates were significantly associated with matching for HLA-A, -B, and -DR antigens in both first and retransplant recipients treated with a sequential protocol of OKT3/CsA (P < 0.01). Among patients with preformed panel reactive lymphocytotoxic antibodies > 50%, significantly better 3-year graft survival rates were obtained with sequential OKT3/CsA than were achieved without OKT3 in first transplant recipients (80 +/- 5% vs. 63 +/- 1%, respectively; P < 0.001) and in retransplant recipients (73 +/- 5% vs. 58 +/- 1%, respectively; P < 0.01). Significantly improved 3-year graft survival rates with OKT3 and sequential CsA were likewise obtained in two other groups of high-risk patients: black recipients (P < 0.001) and pediatric recipients (P < 0.01). The results demonstrate an advantage for OKT3 prophylaxis in conjunction with delayed CsA therapy among renal transplant recipients at high immunological risk, particularly among presensitized patients.

Monitoring of allograft recipients for the development of HLA-specific antibodies: elimination of OKT3 as a complicating factor

In this report we demonstrate that the use of immunoabsorbent beads to remove the OKT3 monoclonal antibody (MoAb) from the sera of transplant recipients is necessary in order to avoid the false positive reactivity in panel reactive antibody (PRA) assay. We have shown that the presence of OKT3 MoAb in patient's sera can give a positive reactivity in PRA, which may be interpreted as antibody development. Rabbit antimouse immunoglobulin covalently linked to sepharose can effectively remove the OKT3 MoAb from patients sera, but has no effect on anti-HLA antibodies. The absorbance of OKT3 MoAb, therefore, is necessary to obtain accurate results in respect to humoral rejection, which may lead to mismanagement of patients.