Treatment of Guillain-Barré syndrome with anti-T cell monoclonal antibodies

Three patients with acute Guillain-Barré syndrome were treated early in the course of the disease with OKT3, an anti-T-cell monoclonal antibody. Each patient developed acute lymphopenia with specific depletion of T3-positive lymphocytes. Two patients had continued progression of clinical deficits for eight and 14 days. This suggests that T lymphocytes may not be essential for progression of Guillain-Barré syndrome at this stage of the disease.

Regulation of stimulus-induced calcium transport pathways in human T (Jurkat) lymphoblasts

In human T (Jurkat) lymphoblasts we have studied the calcium signals induced by monoclonal antibodies reacting with the T-cell antigen receptor complex (TCR and CD3). Jurkat cells were preloaded with the fluorescent calcium indicator Indo-1 and the stimulus-induced rise in cytoplasmic free calcium concn was followed in the absence or in the presence of external calcium. The technique allowed the separate investigation of the intracellular calcium release and the external calcium influx processes. The changes in the membrane potential of Jurkat cells were followed simultaneously by using fluorescent indicators. We found that the activation of protein kinase C by phorbol ester (PMA) or by the permeable diacyl glycerol, DiC8, rapidly eliminated the calcium signal, independently of the presence or absence of external calcium, while these treatments did not appreciably change the membrane potential. In contrast, cell membrane depolarization achieved by various treatments selectively blocked the stimulus-induced calcium influx, while did not affect stimulus-induced calcium release from internal stores. The magnitude of the stimulus-induced calcium influx was found to be largely independent of the external calcium concns between about 2-2500 microM. It is demonstrated that the inhibitory effect of membrane depolarization on calcium influx is not simply due to the reduction of the inward calcium gradient under these conditions. These observations indicate a significant down-regulation of the stimulus-induced calcium signal by protein kinase C activation and a selective inhibition of the receptor-operated calcium channels by membrane depolarization.

Different activation states of human lymphocytes after antibody-mediated stimulation via CD3 and the alpha/beta T-cell receptor

BMA031 is an IgG2b antibody directed towards the human alpha/beta T-cell receptor that is able to induce proliferation of peripheral blood mononuclear cells independent of antibody crosslinking. The proliferative response to BMA031 during the first 3 days of culture is usually of similar magnitude to that induced by the IgG2a CD3 antibody OKT3 but decreases quickly afterwards. Stimulation by BMA031 induces no measurable IL-2 release, very low expression of the IL-2 receptor, and does not trigger cytotoxic effector function. However, cross-linking of the antibody or addition of IL-2 leads to enhanced and prolonged proliferation, strong IL-2 receptor expression, and cytotoxic activity, features that are usually found after stimulation by the IgG2a CD3 antibody OKT3 in soluble form. The stimulatory effect of BMA031 cannot be diminished by IL-2 receptor blocking, whereas stimulation by OKT3 is strongly reduced. Moreover, proliferation induced by BMA031 has lower sensitivity to inhibition by ciclosporin than OKT3. From these results two major conclusions can be drawn: (1) an IL-2-independent way of activation may be important for the short-term proliferation of the T cells stimulated by BMA031 and (2) after stimulation by BMA031, cells reach a state of activation that is different from that induced by OKT3. These differences are most likely related to the different specificities of the antibodies, alpha/beta TcR versus CD3, suggesting that different activation signals are triggered via CD3 and via the alpha/beta TcR.

The carbohydrate structures of a mouse monoclonal IgG antibody OKT3

A mouse monoclonal antibody OKT3, of IgG2a isotype, was isolated from hybridoma culture fluid. Sugar analysis showed the presence of sialic acid, galactose, mannose, fucose, and N-acetylglucosamine, i.e. sugars typical for N-glycosidically linked carbohydrate chains. The absence of N-acetylgalactosamine revealed that O-glycosidically linked carbohydrates were not present. The purified antibody was reduced, alkylated, and separated into heavy and light chains, and all carbohydrates were shown to be associated with the heavy chains. The N-linked carbohydrate chains were isolated as alditols using strong alkaline-borohydride degradation and further fractionated on a concanavalin A-Sepharose column and high performance ion exchange chromatography with pulsed amperometric detection. Structural analysis was carried out on the isolated oligosaccharide alditols by chemical analyses, fast atom bombardment mass spectrometry, and 500-MHz 1H NMR spectroscopy. Triantennary and biantenary types of structures were found. The triantennary structures were present as trisialo and tetrasialo forms without fucose; the tetrasialo forms were shown to contain a sequence of Neu5Ac alpha 2-3Gal beta 1-3[Neu5Ac alpha 2-6]GlcNAc beta 1- on one of the branches. The biantennary structures were present as completely sialylated nonfucosylated species and as asialo-, agalacto-, and partially fucosylated structures.

Meningism in a ten-month-old infant during OKT3 therapy

Organ transplantation has become widely applied as a therapy of end-stage organ dysfunction and is finding increasing application in the pediatric population. This has become possible largely through the use of improved immunosuppressive agents, such as OKT3. Aseptic meningitis associated with OKT3 has been previously reported, with a frequency rate of 3% to 14%, in adult renal allograft recipients. Aseptic meningitis after OKT3 therapy has not been reported in children. Meningitis, however, is a frequent infection encountered in young children, and the development of meningeal irritation during therapy with OKT3 may present a diagnostic dilemma. We describe aseptic meningitis in a 10-month-old infant after treatment of cardiac allograft rejection with OKT3.

Anti-CD3 monoclonal antibody induction therapy. Immunological equivalency with triple-drug therapy in heart transplantation

This study examines the hypothesis that induction immunosuppressive therapy with murine anti-CD3 monoclonal antibodies (OKT3) reduces the frequency of rejection episodes in heart transplant recipients receiving 3-drug maintenance therapy with cyclosporine, azathioprine, and steroids. A group of 26 adult heart transplant recipients requiring preoperative intravenous inotropic drugs or with elevated serum creatinine received OKT3 induction as well as long-term triple drug therapy. Cyclosporine was withheld for the first 4 postoperative days allowing for resolution of cardiogenic renal dysfunction. A corresponding group of 26 heart transplant recipients received triple drug therapy alone started immediately before transplantation. Both groups were comparable in age, sex distribution, and follow-up period. The frequency of rejection episodes was identical for the two groups (0.003 episodes per patient month). Time to first rejection episode in the induction group, however, was delayed twofold as compared with the noninduction group (42 versus 21 days, p less than 0.01). Actuarial survival at 6, 12, and 18 months was 88%, 81%, and 81% for the induction group and 92%, 92%, and 87% for the noninduction group (p = NS). Treatment for rejection was not required in 35% of the induction group and 38% of the noninduction group (p = NS). OKT3 provides satisfactory immunosuppression in heart transplant recipients with hemodynamic or renal compromise, yet it does not reduce the frequency of rejection episodes compared with patients receiving triple drug therapy alone. Although the time to first rejection may be delayed, routine adjuvant use of OKT3 for induction in all heart transplant recipients may incur needless expense without providing an important immunological advantage as compared with triple drug immunosuppression alone.

Therapy of refractory, recurrent heart rejection with multiple courses of OKT3

The treatment for recurrent cardiac allograft rejection refractory to conventional immunotherapy is retransplantation. When retransplantation is not possible, alternative approaches must be undertaken. This report reviews the successful management of persistently recurring rejection using five serial 14-day courses of OKT3 in a 35-year-old man after two heart transplantations.

Cardiac allograft function with corticosteroid-free maintenance immunosuppression

Potent prophylactic immunosuppressive protocols promote the safe withdrawal of corticosteroid maintenance. The benefits of corticosteroid-free maintenance immunosuppression include the absence of the cushingoid habitus, fewer infections, less obesity, and lower serum cholesterol. The incidence of allograft coronary artery disease is not increased by corticosteroid-free maintenance. To assess the long-term effects of corticosteroid-free immunosuppression on allograft function, we compared results of hemodynamic study and noninvasive evaluation over the 2-year follow-up of 57 patients on corticosteroid-free maintenance to 40 patients who required corticosteroid. Age and pretransplantation diagnoses were similar, but a greater percentage of those who required corticosteroid maintenance were female (28% versus 2%, p less than 0.001). Indexes of allograft function were similar in both groups and these indexes included ejection fraction, right atrial pressure, pulmonary artery pressure, pulmonary capillary wedge pressure, cardiac index, left ventricular end-diastolic dimension, and posterior wall thickness. Patient survival was identical in the two groups (98%). These data indicate that corticosteroids can be safely withdrawn with the subsequent early benefits and without compromising long-term allograft function.

Relationship of OKT3 sensitization and vascular rejection in cardiac transplant patients receiving OKT3 rejection prophylaxis

We prospectively and serially monitored plasma levels of OKT3 in 20 patients who were receiving 14- or 21-day rejection prophylaxis with OKT3. We retrospectively compared plasma OKT3 levels with biopsy scores assessed by light microscopy and immunofluorescence, clinical findings, human antimouse antibody (HAMA) production assessed by a blocking assay and by ELISA, and circulating immune complex levels assessed by a flow cytometric Raji cell assay. Using these methods, we evaluated the relationship of OKT3 sensitization, a humorally mediated immune response, to the development of vascular rejection in these patients. We found that 6 of 20 patients had declines in plasma OKT3 levels to less than 50% of their steady-state value before the conclusion of therapy (OKT3 consumption). This fall in plasma OKT3 preceded a significant rise in the CD 3 lymphocyte level by up to 3 days. All 6 patients showed HAMA production by either blocking or ELISA assay (P = less than 0.02) and developed vascular rather than cellular rejection (P = less than 0.01). OKT3 sensitization was significantly more common in patients treated with 21-day rejection prophylaxis (4 of 6 patients, P = less than 0.01). Only 4 of 14 other patients showed vascular rejection; 2 of these 4 also developed HAMA without OKT3 consumption and both had been treated with 21-day rejection prophylaxis with OKT3. None of the 20 patients showed significant levels of circulating immune complexes. This study demonstrates that OKT3 sensitization is strongly associated with vascular rejection. Vascular rejection was usually demonstrated 7 days after OKT3 consumption was seen and was coincident with HAMA production. By contrast, 4 patients without OKT3 sensitization had vascular rejection demonstrable in the early posttransplant period; in such patients, prospective immunofluorescence of biopsies was the only reliable indicator of this rejection type. The higher incidence of vascular rejection in these 20 patients was definitely related to the use of 21-day OKT3 rejection prophylaxis. Overall, 7 of the 12 patients treated with this regimen developed vascular rejection. Allograft and patient survival among patients with vascular rejection was significantly worse than in patients with cellular rejection (P = less than 0.01). Prospective monitoring of patients treated with OKT3 by serial plasma levels and by biopsy immunofluorescence will identify patients at risk for these types of humoral rejection.

Inhibition of IL-2 receptor induction and IL-2 production in the human leukemic cell line Jurkat by a novel peptide inhibitor of protein kinase C

We recently reported that the myristoylated peptide N-myristoyl-Lys-Arg-Thr-Leu-Arg (N-m-KRTLR) is a novel protein kinase C inhibitor. In this study, we investigated the biological effects of N-m-KRTLR using as an in vitro model the induction of the IL-2 receptor and IL-2 secretion by Jurkat cells in response to stimulation with 12-O tetradecanoylphorbol-13-acetate (TPA) plus phytohemagglutinin (PHA) and TPA plus OKT3 mAb. N-m-KRTLR significantly suppressed induction of the IL-2 receptor on the surface of the Jurkat cells by TPA plus either PHA or OKT3 mAb. Furthermore, N-m-KRTLR inhibited the production and release of IL-2 from cultured Jurkat cells stimulated with TPA plus either PHA or OKT3 mAb. Similarly, this peptide significantly inhibited the IL-2 production in normal human peripheral blood mononuclear cells in response to stimulation by TPA and PHA. In contrast, this peptide did not affect expression of the CD3 complex on the surface of the Jurkat cells either alone or in the presence of TPA or PHA. Furthermore, N-m-KRTLR did not interfere with the spontaneous proliferation of the Jurkat cells, and its effects on IL-2 secretion and IL-2 receptor expression in the Jurkat cells were evident without loss of cell viability. These results suggest that the novel protein kinase C inhibitor N-m-KRTLR may selectively inhibit certain activation pathways of Jurkat cells and indicate the usefulness of N-m-KRTLR in the analysis of discrete events in T cell activation.

Unique antithymocyte serum versus OKT3 for induction immunotherapy after heart transplantation

To determine the efficacy of a unique polyclonal rabbit antithymocyte serum (ATS), we compared 17 consecutive nonrandomized heart transplant recipients (mean age, 38 +/- 15 years) given a 7-day prophylactic postoperative course of locally produced ATS (whole serum, no Freund's adjuvant, IV) with 19 patients (mean age, 42 +/- 17 years) given 14 days of monoclonal antibody OKT3. Cyclosporine, steroid, and azathioprine dosages were similar. At 30 days the event-free incidence of rejection was 66% +/- 11% for OKT3 (2.3 events/100 patient-days) versus 47% +/- 12% for ATS (1.2 events/100 patient-days). At 60 days and thereafter, however, there was no difference in overall number of cumulative rejection episodes. Overall infection rates were similar in both groups: the ATS group tended to have more bacterial infections, whereas the OKT3 group displayed more viral infections. Antiidiotypic antibodies developed in 29% of the ATS group and in 22% of the OKT3 group. This report demonstrates the efficacy of this polyclonal serum preparation made without Freund's adjuvant when used as an adjunct for induction-prophylactic immunotherapy in heart transplant recipients when compared with OKT3.

Acute renal allograft rejection: the role of monoclonal antibodies in treatment: experience with orthoclonal anti-T3 cell antibody

We have reviewed the literature relating to the use of monoclonal antibodies in acute renal allograft rejection. More emphasis has been placed on Orthoclone OKT3 which has been more commonly used and summarise our experience with its use as rescue therapy in renal allograft rejection.

Role of interleukin-2 and interleukin-6 in the mitogen responsiveness of T cells from patients with 'common-variable' hypogammaglobulinaemia

We have assessed the ability of interleukin-2 (IL-2) and interleukin-6 (IL-6) to augment the proliferative response of T lymphocytes from 'common-variable' hypogammaglobulinaemia (CVH) patients and from normal controls, to the mitogens phytohaemagglutinin (PHA) and OKT3. We show that with cells from the control group and from those patients whose T cells respond to PHA within the control range, both IL-2 and IL-6 will significantly augment the response to OKT3. However, in those patients with a T cell defect in which the PHA response is below the control range, neither IL-2 nor IL-6 could restore the PHA or OKT3 response to normal. Responses to IL-2 or IL-6 alone were always in or above the control range.