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PubMed1993

Selective targeting of human lymphokine-activated killer cells by CD3 monoclonal antibody against the interferon-inducible high-affinity Fc gamma RI receptor (CD64) on autologous acute myeloid leukemic blast cells.

The potential of the CD3 monoclonal antibody (MoAb) OKT3 to selectively target lymphokine-activated killer (LAK) cells and T-cell clones in vitro against autologous tumor cells was studied using material from patients with acute leukemias (19 acute myeloid leukemias [AML], and 3 acute lymphoblastic leukemias [ALL]). Cytotoxicity mediated by patient LAK cells against AML blasts, but not against ALL cells and autologous Epstein-Barr virus-transformed B cells, was enhanced 1.5-fold to 9.3-fold by OKT3 in all AML patients studied. The following findings suggest that the major target molecule on AML cells for OKT3-coated LAK cells is the high-affinity Fc receptor for IgG (Fc gamma RI; CD64): (1) susceptibility to killing by OKT3-coated effector LAK cells segregated with target cell expression of CD64; (2) preincubation of AML blasts with monomeric OKT3 (murine IgG2a), the Fc portion of which is known to have preferential binding affinity to CD64, resulted in lysis by autologous T cells that were not spontaneously cytotoxic; (3) OKT3-dependent increase in lysis of primary and relapsed AML cells by autologous T-cell clones correlated with the amount of target cell expression of CD64; (4) anti-leukemic cytotoxicity of OKT3-coated T cells could partially be inhibited by monomeric human Ig, the natural ligand of CD64; and (5) expression of CD64 (Fc gamma RI) on fresh AML cells could be increased by interferon-gamma (IFN-gamma) and IFN-alpha translating into further enhancement of lysis by autologous OKT3-coated LAK cells. Nonmalignant CD34+ cells sorted from peripheral blood were found to lack expression of CD64 and hence were not affected by OKT3-triggered T-cell targeting, as detected by colony formation assays. In conclusion, the in vitro data presented provide a rationale for the combined clinical use of recombinant interleukin-2, IFN-gamma, and low doses of CD3 MoAb to eliminate AML cells while sparing nonmalignant hematopoietic progenitor cells, for example, in the setting of purging procedures for autologous bone marrow transplantation.

Antigens, CD↗
PubMed1995

A randomized prospective trial of prophylactic immunosuppression with ATG-fresenius versus OKT3 after renal transplantation.

We carried out a randomized prospective trial to compare OKT3 (5 mg/d, 51 patients) with ATG-Fresenius (ATG-F, 4 mg/kg/d, 53 patients) for induction therapy after renal transplantation, concerning side effects, rejection, and infection incidence within a one year follow-up period. Concomitant immunosuppression included azathioprine/steroids from day 0 and cyclosporine A from day 4. OKT3 patients experienced significantly more and more-severe side effects, particularly pyrexia, headache, and pulmonary fluid overload. One-year graft survival was excellent in the ATG-F group (91%), but only 78% in the OKT3 group (P < 0.05) due to a series of rejections that occurred beyond day 100; patient survival (96% and 92%) was similar in both groups. OKT3-treated patients experienced more biopsy-proven rejections (0.6 +/- 0.1/pt.) than ATG-F patients (0.3 +/- 0.1, P < 0.05), and there was a similar, albeit not significant trend in clinical rejections (OKT3: 1.1 +/- 0.2/pt.; ATG-F: 0.8 +/- 0.1/pt.). Infections were more common in the OKT3 group (OKT3: 3.2 +/- 0.3, ATG-F: 2.0 +/- 0.2, P < 0.05), although this was entirely attributable to "minor" infections. On days 1 through 6, CD3 counts were more profoundly depressed with OKT3 therapy. Beyond day 10, however, CD3 counts were lower in the ATG-F group, as were CD2 counts, CD4 counts, and the CD4/CD8 ratio, suggesting a more prolonged immunosuppressive effect of ATG-F. Sensitization occurred more frequently with OKT3 (31%) than with ATG-F (10%), but was usually irrelevant, except in two patients (one in each group), whose grafts were lost because of immunization against OKT3 and ATG-F, respectively. In conclusion, a 7-day induction therapy with OKT3 does not improve outcome or diminish immunological graft loss when compared with ATG-F, but is associated with more rejections, infections, and side effects. ATG-F appears to be preferable for induction immunosuppression after renal transplantation.

Adult↗
PubMed1994

Increase of sTNF receptor levels in acute renal allograft rejection after treatment with OKT3.

The use of OKT3 is associated with severe clinical side-effects. Adverse reactions are partly attributed to release of tumour necrosis factor (TNF). TNF binds to two receptors on the outer membranes of most human cell lines. Shedding of these proteins (sTNFR-p55 and sTNFR-p75) may block biological effects of TNF. Here we show a fair correlation between serum levels of sTNFRs and renal function as measured by glomerular filtration rate (GFR). In addition we assessed levels of sTNFR-p55 and sTNFR-p75, corrected for reduced renal clearance, in renal allograft rejection and following treatment with OKT3. Corrected serum levels (CSL) of sTNFR-p55 and sTNFR-p75 were determined in 12 renal allograft patients treated for an acute rejection episode with either OKT3 or methylprednisolone (MPNS). Serum levels of CSLsTNFR-p55 and CSLsTNFR-p75 in both groups prior to anti-rejection treatment were not elevated. CSLsTNFRs peaked at 1 h after the administration of OKT3, whereas in the MPNS group CSLsTNFRs remained unchanged. We conclude that in acute renal transplant rejection CSLsTNFRs increase after treatment with OKT3. In spite of high circulating sTNFRs levels all OKT3-treated patients suffered from clinical side-effects.

Adult↗
PubMed1995

Effects of the Th1 and Th2 stimulatory cytokines interleukin-12 and interleukin-4 on human immunodeficiency virus replication.

The cytokines interleukin-12 (IL-12) and IL-4 play important roles in the development of Th1-like (type-1) and Th2-like (type-2) T-cell responses, respectively, and there is evidence that type-1/type-2 T helper imbalances are important in the pathogenesis of human immunodeficiency virus (HIV) disease. With this background, we examined the effects of these cytokines on HIV replication. Neither stimulated HIV replication in fresh peripheral blood mononuclear cells (PBMC). However, in prestimulated PBMC, IL-12, and to a greater extent, IL-4 as well as IL-2, induced production of HIV p24 antigen over 7 days of culture (no cytokine 3,900 x/divided by 1.31 [GM x/divided by SEM] pg/mL; IL-12, 34,300 x/divided by 1.39 pg/mL; IL-4, 283,000 x/divided by 1.14 pg/mL; and IL-2, 328,000 x/divided by 1.31 pg/mL). Neither IL-12- nor IL-4-induced HIV replication was attributable to induction of IL-1, IL-2, tumor necrosis factor (TNF)-alpha, or TNF-beta. Both IL-12- and IL-4-induced HIV replication was associated with selective loss of the CD4+ subset in stimulated cultures. IL-4 stimulated HIV replication in monocyte/macrophages, while IL-12 had little or no effect in these cells. Finally, HIV replication stimulated by IL-12 or IL-4 was inhibited by dideoxynucleosides. Thus, IL-12 and IL-4 enhance HIV replication and HIV-induced cell death in prestimulated PBMC. Through killing of the CD4+ T cells stimulated by these cytokines, this may result in inappropriate type-1/type-2 responses in HIV-infected patients and contribute to their Th1 immunodeficiency.

Antibodies, Monoclonal↗
PubMedDate not supplied

Association of pretransplantation antiheart antibodies with clinical course after heart transplantation.

METHODS: Sera from 129 patients awaiting heart transplantation were assayed for the presence of IgM and IgG antiheart antibodies by means of sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blotting. The patients' posttransplantation clinical course was assessed with regard to the amount of methylprednisolone, rabbit antithymocyte globulin, and OKT3 anti-T cell antibody, and the number of biopsy-confirmed rejection episodes. Before undergoing heart transplantation, approximately half the patients had weak IgM (45%) and weak IgG (48%) antiheart antibodies. However, 22.5% of the patients had strong IgM antiheart antibodies before transplantation, and they required more methylprednisolone than those who were negative and weak and approximately twice as much rabbit antithymocyte globulin as those who were negative, weak, or moderate. Six of the patients in this group required OKT3 therapy, and additionally they had a significantly greater number of rejection episodes than those patients who were negative (p = 0.006), or who had weak antiheart antibodies before transplantation (p = 0.001). RESULTS AND CONCLUSIONS: Analysis of the pattern of banding of strong IgM antiheart antibody sera showed antiheart antibodies most frequently against myocardial proteins of 35, 42, 50, 60, 70, 110, 120, 150, 180, and 200 kDa. Several of these proteins were characterized by two-dimensional polyacrylamide gel electrophoresis and Western blotting as tropomyosin (35 kDa), actin (42 kDa), heat shock protein 60 (60 kDa), and heat shock protein 70 (70 kDa). All strong antiheart antibody sera showed reactivity against a 200 kDa protein corresponding to myosin heavy chain.

Adult↗
PubMedDate not supplied

Efficacy of low-dose OKT3 as cytolytic induction therapy in heart transplantation.

BACKGROUND: The need for prophylactic cytolytic treatment in heart transplantation is a controversial issue. Its use, however, might prevent the onset of cellular rejection in the immediate postoperative period, facilitating patient management. It has recently been suggested that the administration of these products at low doses might have the same immunologic impact and would reduce secondary effects and the cost of treatment. METHODS: In a nonrandomized retrospective study, we assessed 45 consecutive patients who underwent orthotopic heart transplantation in 1992 and 1993. Six patients who died before receiving the complete OKT3 dose were excluded. Twenty-three patients were treated with 5mg/day doses of OKT3 for 7 consecutive days. Another 16 patients received 2.5 mg of OKT3 for 7 consecutive days. RESULTS: There were no significant differences between the two groups with respect to CD3 counts on days 2 (0.1% +/- 0.3% versus 0.04% +/- 0.25%; p > 0.05) and 6 (0.2% +/- 0.45% versus 0.1% +/- 0.3%; p > 0.05), number of rejection episodes (1.45% +/- 0.8% per year of follow-up versus 1.7% +/- 1.2%, p = 0.66), number of infectious complications (8 versus 3, p > 0.05), total methylprednisolone dose used to treat rejection crises (3900 +/- 2765 versus 3600 +/- 1963 mg; p = 0.71), adverse effects attributed to OKT3 (two versus none), or length of the postoperative hospital stay (36.8 +/- 19 versus 30.2 +/- 20.9 days). CONCLUSIONS: As cytolytic induction therapy in heart transplantation, a daily regimen of 2.5 mg of OKT3 for 7 days achieves the same clinical and immunologic effect as the conventional 5 mg/day dose. In addition, it results in a considerable reduction in the cost of treatment.

Azathioprine↗
PubMedDate not supplied

Reliability and usefulness of immunofluorescence in heart transplantation.

BACKGROUND AND METHODS: To study the reliability and usefulness of immunofluorescence on heart biopsy specimens for routine monitoring of heart transplant recipients for rejection, frozen sections of 72 consecutive endomyocardial biopsy specimens from 18 heart transplant recipients during the first 6 weeks after transplantation (and later) and from 11 control specimens from donor hearts and other nontransplantation patients were studied. Fifteen patients received OKT3 induction. The diagnosis of vascular (humoral) rejection pattern as defined by Hammond was based on the microvascular deposition of immunoglobulin and C3 or C1q. Echocardiographic data and right-sided heart catheterization were obtained simultaneously. RESULTS: The results showed that immunofluorescence was positive for a vascular rejection pattern in 60% (43 of 72) overall, in heart transplant recipients it was positive in 59% (36 of 61), and in control subjects it was positive in 63% (7 of 11). Most of the patients who had positive immunofluorescence had no hemodynamic compromise. Humoral rejection was not predicted by positive immunofluorescence in our study. We also found no correlation with either positive or negative immunofluorescence for the short-term or long-term outcome during the first 6 weeks after transplantation. CONCLUSION: The usefulness of routine immunofluorescence in all surveillance heart biopsies is questionable as determined by this study.

Adult↗
PubMed1995

Expanding indications for biotechnology agents.

Many biotechnology products currently on the market were initially approved for indications affecting only a small number of patients. However, pharmaceutical manufacturers have continued to study these agents for potential new therapeutic uses. The result is that several of these products are now approved for multiple uses involving large patient populations. In many cases, the biotechnology agents are being used in patients for whom no effective therapy was previously available.

Biotechnology↗
PubMed1994

Ion exchange resins for the purification of monoclonal antibodies from animal cell culture.

We have compared various ion exchangers for monoclonal antibody (MAb) purification using different starting materials such as ascitic fluid and cell culture supernatant. Twelve cation and anion exchange resins were tested so far. Purification of MAbs with regard to the starting material is described. In well-defined conditions of adsorption (20 mM MES buffer, pH 6.50), one purification step based on cation-exchange chromatography is generally sufficient to achieve at least 90% purity of the MAb, even when produced by animal cell culture. Cation-exchange supports exhibit higher capacity for MAbs compared to anion exchangers. Among the cation exchangers tested, we have selected the cross-linked matrix S Sepharose FF for its large specificity and capacity for MAbs. Considering these key parameters and also the good mechanical resistance of the S Sepharose FF, we describe how, by varying the flow rate, sample concentration, and size of the column, the productivity may be improved in a monoclonal antibody purification process. Finally, a general 'gram scale' purification protocol of MAbs produced by animal cell cultures is proposed. This protocol, based on economical adsorption conditions and three steps of elution (100 mM, 200 mM and 1 M NaCl), allows the recovery of highly purified MAbs.

Animals↗
PubMedDate not supplied

Intragraft monitoring of rejection after prophylactic treatment with monoclonal anti-interleukin-2 receptor antibody (BT563) in heart transplant recipients.

BACKGROUND: Anti-interleukin-2 receptor monoclonal antibodies have been used successfully in the prevention of rejection in cardiac allografts in several animal models. METHODS: In an open randomized study murine monoclonal CD3 antibody and BT563, a murine anti-interleukin-2 receptor monoclonal antibody, were given as rejection prophylaxis during the first week after heart transplantation. Cyclosporine therapy was initiated at the third postoperative day. RESULTS: In half the BT563-treated patients an early rejection was histologically shown at week 1, whereas heart transplant recipients treated with murine monoclonal CD3 antibody had a rejection incidence at week 1 of only 9%. During BT563 treatment CD25-positive cells (i.e., cells bearing the interleukin-2 receptor) were not detectable in peripheral blood. However, immunohistologic studies of endomyocardial biopsy specimens taken 1 week after transplantation showed the presence of CD25-positive cells within these specimens in 8 of 10 (80%) of patients with rejection. In patients without rejection CD25-positive cells were present in the biopsy specimens of only two of nine patients (22%). Reverse-transcriptase polymerase chain reaction studies on biopsy material showed the presence of messenger RNA for the interleukin-2 receptor in all and for interleukin-2 in three of five (60%) of biopsy specimens of rejecting grafts. CONCLUSIONS: Although CD25-positive cells were not detectable in peripheral blood during BT563 treatment, these cells were at the same time found to be present within 80% of the endomyocardial biopsy specimens from the rejecting grafts. By initiating cyclosporine treatment at day 0, the synergistic effect of combining cyclosporine and anti-interleukin-2 receptor monoclonal antibodies may result in a lower rejection incidence.

Animals↗
PubMedDate not supplied

Acute rejection: significance of elapsed time after transplantation.

In July 1990 the new standardized grading scheme for the International Society for Heart and Lung Transplantation was established. One of the purposes of "splitting" the grades was to learn the significance and outcome of the various grades proposed. Between January 1990 and November 1992, 263 grade 1A, 19 grade 1B, and 100 grade 2 "new" rejection episodes were identified at our institution. These episodes occurred in 86 adult recipients who underwent transplantation between January 1990 and August 1992 and 98 recipients who underwent transplantation before January 1990, in whom the episodes occurred more than 1 year from the date of transplantation. The outcome of the episode was determined on subsequent endomyocardial biopsy samples to be resolution or "progression" to a higher grade. The percentage of focal mild (grade 1A) rejection episodes progressing to a moderate (grade 3A) rejection in the first 6 months after transplantation was 24.4% (20 of 82) compared with a progression rate of 5.1% (3 of 59) and 2% (3 of 149) in episodes occurring beyond 6 months and 1 year after transplantation, respectively (p < 0.005). Of the focal moderate (grade 2) rejection episodes receiving no augmentation of immunosuppression, 35.7% (5 of 14) occurring within the initial 6 months and 7.3% (3 of 41) of all such episodes diagnosed beyond 1 year after transplantation progressed to a moderate rejection. A similar trend was seen in the focal moderate rejection episodes that received augmentation of immunosuppression: 26.3% (5 of 19) of episodes occurring within 6 months and 0 of 15 of all episodes occurring beyond 1 year after transplantation progressed to a moderate rejection.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗