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Biomedical subjects

A B Cosimi

Publications and source records attributed to A B Cosimi.

At least 127 records · Page 7Linked to original sources
PubMed1990

In vivo effects of monoclonal antibody to ICAM-1 (CD54) in nonhuman primates with renal allografts.

These studies test whether allograft rejection can be blocked by interference with leukocyte adhesion, using a murine IgG2a mAb (R6.5) reactive with monkey ICAM-1 (CD54). In 16 Cynomolgus renal allograft recipients, R6.5 was administered prophylactically as the sole immunosuppressive agent for 12 days (0.01 to 2 mg/kg/day). Survival in 14 recipients with technically successful grafts was significantly prolonged (24.2 +/- 2.4 vs 9.2 +/- 0.6 days for controls; p less than 0.001). Intercellular adhesion molecule-1 (CD54) (ICAM-1) was expressed on vascular endothelium in the kidney and other organs in the monkey in a pattern similar to that in humans. During cellular rejection in controls, ICAM-1 expression increased on endothelial cells, infiltrating mononuclear leukocytes and tubular cells. Biopsies during R6.5 administration showed decreased T cell infiltration (CD2, CD8, CD4) compared with controls and decreased arterial endothelial inflammation. No changes occurred in circulating T cells, aside from variable coating with mIgG. In six of eight other recipients R6.5 administration (0.5 to 2 mg/kg/day for 10 days) reversed preexisting rejection that resulted from taper of Cyclosporine to subtherapeutic levels. Responding grafts showed decreased edema and hemorrhage but no consistent change in the infiltrate. At 1 h after the first dose, mouse IgG deposited primarily on the graft vascular endothelium without any change in the inflammatory infiltrate. Mouse IgG also deposited on the endothelium of normal organs without eliciting an inflammatory response and was cleared from the endothelium within 4 days. Inasmuch as the principal site of binding was the vascular endothelium, we hypothesize that the antibody blocks adhesion to graft ICAM-1 molecules on the vessels. Anti-ICAM-1 also binds to recipient cells and may interfere with Ag presentation and/or T cell interactions. Whatever the mechanism(s), these studies indicate that an anti-ICAM-1 antibody inhibits T cell mediated injury in vivo, and that ICAM-1 is a critical molecule in the pathogenesis of allograft rejection.

Animals↗
PubMed1990

A randomized clinical trial of prophylactic OKT3 monoclonal antibody in liver allograft recipients.

Seventy-nine hepatic allograft recipients were randomized to receive either conventional immunosuppression, including cyclosporine, azathioprine, and steroids (41 patients), or investigational therapy in which OKT3 replaced cyclosporine during the first postoperative week (38 patients). Early rejection occurred in 29 patients (71%) in the conventional group and 15 patients (39%) in the OKT3 group. Posttransplantation renal dysfunction occurred in 12 patients (29%) in the conventional group and 6 patients (16%) in the OKT3 group. Mean initial hospital stay was 34.1 +/- 18.8 days in the conventional group compared with 29.1 +/- 16.8 days in the OKT3 group. Cumulative patient survival (mean follow-up, 17.8 +/- 7.1 months) was 73.2% (30/41) for the conventional group and 84.2% (32/38) for the OKT3 group. Prophylactic OKT3 is indicated especially for liver allograft recipients with other complicating conditions that make management of early rejection unusually difficult.

Adult↗
PubMed1990

Long-term, low-dose cyclosporine treatment of renal allograft recipients. A randomized trial.

Ninety-two adult renal allograft recipients, receiving baseline immunosuppression with CsA and prednisone, were assigned randomly to one of the following regimens. CsA was discontinued (D/C group) in 47 recipients who were then maintained on Aza and prednisone; or Aza was added to continued low-dose CsA and prednisone (triple drug [TD] group) in 45 patients. Entry into the study required an absence of rejection and a stable creatinine for at least four months prior to randomization. The mean month of randomization was 8.34 +/- 2.9 for the D/C group, and 7.2 +/- 3.2 for the TD group. Following randomization, a significantly greater rate of rejection (P less than .01) was observed in the D/C group (40%) than in the TD group (13%). With a mean follow-up of 30 months, 41/47 of D/C allografts (87.2%) and 39/45 TD allografts (86.6%) were functioning. Nevertheless, rejection had a persistent adverse effect on allograft function, in both the D/C and TD groups, up to 36 months following randomization. Parameters such as donor-type and rejection prior to randomization did not identify recipients at risk for rejection following randomization. Therefore, although the CsA withdrawal regimen might be ideal, the opportunity to select appropriate candidates remained elusive. In contrast, the safety of the TD regimen became apparent. Neither significant nephrotoxicity nor hypertension was observed, and the opportunity for less daily prednisone was evident. Despite its additional cost, the TD regimen utilizing indefinite low-dose CsA, is preferred.

Adult↗
PubMed1990

1,000 renal transplants at the Massachusetts General Hospital: improved allograft survival for high-risk patients without regard to HLA matching.

Excellent allograft survival is now routinely accomplished following renal transplantation. Changes in immunosuppression have resulted in a significant improvement in early survival for recipients of primary LRD and CD allografts. In our series, crossmatching techniques which accurately assess alloantibody reactivity and not the degree of HLA mismatch have also permitted successful transplantation of such high-risk groups as recipients of second transplants and highly sensitized recipients. However, a yearly attrition rate of allograft loss persists for all recipients. These long-term observations stress the need for newer approaches to immunosuppression in the future, which include protocols that allow for an indefinite tolerance to incompatible donor antigens.

Adult↗
PubMed1990

Prolonged survival of nonhuman primate renal allograft recipients treated only with anti-CD4 monoclonal antibody.

The immunosuppressive efficacy of the monoclonal antibody OKT4A reactive with human and monkey CD4 cells was evaluated in cynomolgus renal allograft recipients. Low-dose (0.1 to 0.3 mg/kg/day) intact monoclonal antibodies (10 recipients) or F(ab')2 fragments (two recipients) were administered for 12 days. High-dose OKT4A (10 mg/kg) was administered on the day of transplantation as the only suppression in five animals. Four control animals received either no therapy or a monoclonal antibody nonreactive with monkey cells (OKT3). Maximum survival of the control animals and those treated with F(ab')2 was 11 days. Mean survival in the recipients of low-dose OKT4A was 25.4 +/- 4.3 days and in the group receiving high-dose OKT4A it was 39 +/- 6.4 days. All OKT4A-treated animals showed "coating" and CD4 modulation without depletion of circulating T cells. No modulation occurred in the F(ab')2-treated recipients. Serial allograft biopsy specimens showed reduced lymphocyte infiltration that was nearly complete in recipients of high-dose OKT4A. Biopsy-derived donor-reactive cytotoxic T-cell lines were generated regularly from recipients of low-dose, but not high-dose, OKT4A during periods of stable function. All animals treated with monoclonal antibodies developed an immunoglobulin G antimurine humoral response. Thus OKT4A is a potent immunosuppressive agent administered even as a single bolus, and depletion of CD4 cells is not required to suppress rejection. Anti-CD4 monoclonal antibodies may prove useful in patients, perhaps requiring only a limited number of higher-dose injections in the peritransplant period.

Animals↗
PubMed1989

Granulomatous eruption after BCG vaccine immunotherapy for malignant melanoma.

In a patient receiving intralesional bacille Calmette-Guérin vaccine injections for recurrent cutaneous metastases of malignant melanoma of the right leg, a striking eruption developed on that limb only. The eruption consisted of multiple 1 to 2 mm, reddish brown, flat-topped papules, with confluence into plaques. Histopathologic examination showed multiple tuberculoid granulomas within the papillary and reticular dermis; special stains and cultures were negative for mycobacteria.

BCG Vaccine↗
PubMed1989

Variation in patient response associated with different preparations of murine monoclonal antibody therapy.

The sera of 37 renal and 12 liver allograft recipients treated with OKT3 (42), Leu2a (7), or both (2) monoclonal antibodies were serially analyzed by an enzyme-linked immunosorbent assay to determine the humoral response (IgG) to mAb. Anti-mAb IgG to the treatment mAb was detected in the serum of 23 (76%) renal and 6 (50%) liver OKT3 recipients, and all 7 Leu2a renal recipients, usually within 14 days of mAb completion, but never during the first week of Rx. Each of the 7 Leu2a recipients developed reactivity not only to Leu2a isotype (IgG1), but also to OKT3 isotype (IgG2a). In contrast, only 1 of the 42 renal and liver allograft recipients treated with OKT3 developed reactivity to the Leu2a isotype. Blocking studies indicated that the specificity of the response to the treatment mAb was directed at the idiotype--and, in some patients, to the constant domain (isotype) of the mAb administered. The antibody response to an alternate isotype (IgG2a) observed in Leu2a (IgG1)-treated patients most likely resulted from irrelevant immunoglobulin (IgG2a) in the Leu2a preparation. This reactivity appeared to be specific for the IgG2a subclass. Clinicians administering mAb therapy should be aware that various mAb preparations may contain immunoglobulin isotypes unrelated to the therapeutic mAb. Crossimmunization to the irrelevant immunoglobulins may occur, precluding subsequent use of other mAbs sharing similar isotype.

Antibodies, Anti-Idiotypic↗
PubMed1989

Function and surface phenotype of T lymphocytes infiltrating renal allografts in nonhuman primates treated with monoclonal antibodies.

The phenotype and function of T lymphocyte cell lines established in vitro from kidney biopsies at the time of acute cellular rejection were studied using a nonhuman primate renal allograft model. Our objectives were to investigate the function and surface phenotype of cells that infiltrate renal allografts in animals that were untreated, that were given subtherapeutic cyclosporin, or that developed rejection after treatment with monoclonal antibodies to IL-2R B chain (CD25), immune cell adhesion molecule-1 (ICAM-1), or CD8. Lines from allograft biopsies and peripheral blood were expanded in vitro using solely human recombinant IL-2 and analyzed after 6-20 days in culture. We found that the large majority of cells cultured from cynomolgus allografts at the time of acute rejection or, when possible, assayed directly without culture, were CD3+4-8+ T lymphoblasts that possessed donor-specific cytolytic function and an NK-line, cytotoxic activity. In contrast, it was rarely possible to establish T cell lines exhibiting donor-specific cytotoxic activity from the blood except in the absence of immunosuppression or during CsA taper. A stable number of graft-derived CD4+8- cells was only observed in an unsuppressed animal 2 days after transplantation in the absence of manifest signs of rejection. Taken together, the above data indicate that similar T lymphocyte populations associated with allograft rejection are present in acutely rejecting allografts after the various types of immunosuppressive therapy. Since the infiltrating cells were similar to those obtained prior to therapy, recurrent rejection most likely represents cells that have escaped elimination. The T cells derived from monkey grafts differ from those from human renal allografts by the decreased frequency of CD4+ cells. Whether this difference is species-related or therapy-related is not known.

Animals↗
PubMed1989

A critical analysis of serum and urine interleukin-2 receptor assays in renal allograft recipients.

A component of the interleukin 2 receptor (IL-2R) is released in soluble form during T cell activation and can be detected in the blood during acute renal allograft rejection. This study evaluates the diagnostic utility of a sandwich enzyme immunoassay test for serum and urine IL-2R in renal allograft recipients. A rise in serum IL-2R during the week prior to the clinical diagnosis of rejection correlated better with rejection than did isolated serum IL-2R levels or urine values. For the diagnosis of acute rejection, a rise in serum IL-2R (sensitivity 73%, specificity 87%) was comparable in overall test performance to a rise in serum creatinine (sensitivity 70%, specificity 84%). Overall, the two tests had equivalent receiver operating characteristic curves. Because the etiology of false positives in creatinine and IL-2R assays differed (primarily cyclosporine toxicity and infection, respectively), the predictive value of the combined tests was superior to either alone.

Creatinine↗
PubMed1989

Fc-receptor for mouse IgG1 (Fc gamma RII) and antibody-mediated cell clearance in patients treated with Leu2a antibody.

A pilot study was performed to explore the clinical potential of Leu2a antibody in reversing acute renal allograft rejection. Anti-Leu2a, a murine IgG1 monoclonal antibody (mIgG1 mAb), is specific for the CD8 molecule that is expressed in high density on class I reactive T cells. Of the 6 recipients treated with anti-Leu2a, two responded with a complete reversal of rejection with long-term allograft function maintained for over a year. In two other recipients, acute rejection was initially reversed, but later rejection episodes resulted in allograft failure at 2-3 months posttreatment. Rejection in the two other recipients showed no response to Leu2a mAb treatment. Specific depletion of peripheral blood CD8+ cells occurred in four of the six recipients. Even in this small series, it was evident that cell clearance was neither necessary nor sufficient for reversal of rejection. However, a complete correspondence between cell clearance and the ability of the recipients' mononuclear cells to undergo mitogenic response to the mIgG1 anti-CD3 (Leu4) mAb in vitro was noted. Binding of IgG1 mAb to the Fc-receptor (Fc gamma RII/CD32) expressed on blood monocytes is known to be essential for the T cell mitogenic response to soluble mIgG1 CD3 mAb in vitro. Our data suggest that binding to Fc gamma RII may be an essential step in the process of mIgG1 Leu2a mAb-mediated cell clearance in vivo.

Animals↗
PubMed1989

Procurement of a whole pancreas and liver from the same cadaveric donor.

Analogous arterial and portal circulation to the liver and pancreas has heretofore represented an impediment to the simultaneous procurement of a liver and pancreas from the same cadaveric donor. A surgical approach that allows for the retention of sufficient arterial and portal supply to both allografts is described. Variant hepatic arterial anatomy may be technically managed by the use of a donor iliac artery interposition graft.

Adolescent↗