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J C Scornik

Publications and source records attributed to J C Scornik.

At least 19 recordsLinked to original sources
PubMed1995

Detection of alloantibodies by flow cytometry: relevance to clinical transplantation.

Before an organ transplant is performed, donor-recipient compatibility must be established by a crossmatch in much the same way as it is done for blood transfusions. The target antigens in organ transplantation, however, are HLA rather than blood group molecules, and the target cells are lymphocytes instead of red cells. If antidonor antibodies are detected, it is important to know whether they are IgG or IgM, whether they recognize T and/or B cells, and whether the antibody reactivity is weak or strong. These test requirements are better met by flow cytometry than by the standard cytotoxicity technique. A growing body of evidence now indicates that flow cytometry can provide more sensitive and timely crossmatch information than cytotoxicity assays to decide whether or not a transplant should be done. Flow cytometry crossmatch (FCXM) is a new and evolving technique that has already been found to be extremely useful in the clinical transplantation setting, even though significant questions yet remain about the precision and reliability of using flow cytometry to quantify alloantibodies and about the limits of normal reactivity in the assay. This article reviews important technical details of the FCXM and its interpretation and clinical application in transplantation medicine.

Flow Cytometry↗
PubMed1994

Increased antibody responsiveness to blood transfusions in pediatric patients.

Heightened immune responsiveness has been proposed as one of the reasons underlying suboptimal renal transplant results in very young children or African American recipients. Because multiple factors influence graft outcome, it has been difficult to provide experimental evidence to confirm or refute this suggestion. In the present study we measured IgG antibodies with confirmed HLA specificity produced in response to blood transfusions. The patients evaluated were renal transplant candidates who had not had previous pregnancies or transplants. The overall incidence of HLA sensitization was 12%. Age was the most influential factor in sensitization: patients < 20 years old were 4-5 times as likely to produce anti-HLA antibodies than patients > 20 (P = 0.0018). Female patients were also high responders. However, this was explained by the higher proportion of children among nulliparous female patients rather than by differences in gender. In contrast, the antibody response of black and white recipients was similar. The antibody levels in most patients were low and decreased significantly with time. We conclude that the immunoregulatory influences in patients < 20 years old favor the production of anti-HLA antibodies in response to blood transfusions, a fact that may explain some clinical observations in pediatric transplant recipients.

Adolescent↗
PubMed1994

The crossmatch in renal transplantation. Evaluation of flow cytometry as a replacement for standard cytotoxicity.

Flow cytometry (FC) is increasingly being used as a crossmatch procedure in addition to the standard complement-dependent cytotoxicity (CDC) test. In fact, FC offers a number of advantages over CDC and has the potential to become the primary crossmatch technique for cadaveric donor renal transplantation. We evaluated this possibility in 230 patients crossmatched by both CDC and FC. The results showed that when the T cell crossmatch was negative by FC it was always negative by CDC, and that when the T cell results were positive by CDC (IgM antibodies excluded) they were also positive by FC. As expected, a number of tests were T cell-positive by FC but negative by CDC. A T cell CDC crossmatch was more likely to be positive when FC was positive for both T and B cells and when FC results were quantitatively higher. However, FC was unable to consistently predict a positive, dithiothreitol-resistant B cell CDC crossmatch. A policy to transplant patients with negative FC results (70% of the patients evaluated) and not to transplant sensitized patients with FC+ T cell results (10%) would allow us to make a final decision with only FC in 80% of the cases. Actual graft survival was similar for nonsensitized first-transplant candidates with positive (83%) or all patients with negative (86%) FC results. We conclude that FC is sufficient to make a final decision in most cases. Wider utilization will require improvements in the ability of FC to measure B cell antibodies and to quantitate antibodies to T cells.

B-Lymphocytes↗
PubMed1994

Duplicate publication.

Explore the source record for details and available documents.

Duplicate Publications as Topic↗
PubMed1994

Increased incidence of rejection in patients with delayed graft function.

Because of the difficulties in diagnosing rejection in patients with delayed graft function, such patients were routinely biopsied 7-10 days after kidney transplantation. We found histologic evidence of rejection in 48% of the cases during the lst month posttransplant, a proportion that was significantly higher than in patients with immediate graft function. Furthermore, the 2-year graft survival in patients with delayed graft function and rejection, but not in those without rejection, was significantly lower than in patients with immediate function. The results suggest that there is an association between delayed graft function and rejection and that rejection is the component responsible for the decreased graft survival previously reported for patients with delayed graft function.

Adult↗
PubMed1993

Hepatitis C virus infection in kidney transplant recipients.

To determine the prevalence and significance of hepatitis C virus infection in kidney transplant recipients, paired serum samples collected from 100 renal allograft recipients on admission for kidney transplantation and 1 yr after transplantation were tested for antibody to hepatitis C virus with second-generation enzyme immunoassay and recombinant immunoblot assay and for hepatitis C virus RNA with reverse transcription-polymerase chain reaction. Before kidney transplantation, hepatitis C virus antibody was detected with second-generation enzyme immunoassay in 18 patients (12 second-generation recombinant immunoblot assay-positive, 6 second-generation recombinant immunoblot assay-indeterminate). Nine of 12 second-generation recombinant immunoblot assay-positive and 2 of 6 second-generation recombinant immunoblot assay-indeterminate samples were hepatitis C virus RNA positive. In addition, 7 of 82 patients who had no detectable antibody on second-generation enzyme immunoassay or second-generation recombinant immunoblot assay were hepatitis C virus RNA positive. After kidney transplantation, hepatitis C virus antibody was detected in 19 patients (12 second-generation recombinant immunoblot assay-positive, 7 second-generation recombinant immunoblot assay-indeterminate, 14 seropositive for hepatitis C virus antibody). Eleven of 12 patients with second-generation recombinant immunoblot assay-positive results and 4 of 7 with second-generation recombinant immunoblot assay-indeterminate results were positive for hepatitis C virus RNA. Hepatitis C virus RNA was present in 28 patients 1 yr after kidney transplantation. Six patients appeared to have acquired active hepatitis C virus infection 1 yr after kidney transplantation (seroconverted to hepatitis C virus RNA positivity).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Enzyme-linked immunoassay for anti-HLA antibodies--an alternative to panel studies by lymphocytotoxicity.

In order to provide a simple and specific assay for the detection and quantitation of IgG and IgM anti-HLA antibodies in sera, HLA antigens purified from a pool of 240 random donor platelets were used to develop a solid-phase enzyme-linked immunoassay (EIA). The reference values for identifying the presence of IgG or IgM anti-HLA antibodies were determined by assaying sera from 39 healthy individuals without prior HLA alloimmunization. The assay was evaluated by studying sera from 122 patients who had been characterized previously for panel reactive antibodies by the lymphocytotoxicity assay (LCA). A significant linear correlation between two assays was noted (r = 0.8, P = 0.0001). Further analyses of the data demonstrated that the newly developed EIA has 100% specificity and 95.3% sensitivity as compared with the LCA. Additional studies revealed that patients whose PRA increased or decreased over time were in parallel with antibody levels measured by EIA. When the EIA was used to measure anti-HLA antibody titers, it was more sensitive than the LCA. Since the EIA is sensitive, specific, and technically less demanding, it should provide an useful alternative to reduce the number of the more laborious panel studies for monitoring anti-HLA antibody status in candidates for organ transplantation and recipients of blood transfusions.

Adult↗
PubMed1992

Hyperacute and acute kidney graft rejection due to antibodies against B cells.

Because of the perception of its uncertain clinical significance, the B cell crossmatch is not universally performed before renal transplantation. Even though sporadic cases of hyperacute rejection associated with B cell antibodies have been reported, doubts remain in light of other studies suggesting no effect on graft survival. This report describes 4 cases of graft rejection (3 hyperacute and 1 acute) that occurred in patients with anti-B-cell antibodies specific against donor HLA-DR or DQ antigens. Absence of anti-donor class I antibodies was confirmed in all cases by 2-color flow cytometry. Strong evidence for an antibody-mediated mechanism was found in one patient with anti-class I and anti-class II antibodies in serum transplanted with a class II mismatched kidney. In this case, only anti-class II antibodies were recovered in the eluate of the nephrectomy specimen. These four cases were compiled from three different institutions over a four-year period, which confirms the infrequent occurrence of these events. While anti-class II antibodies may not always be detrimental for graft survival, these results also confirm that they have the potential to cause hyperacute or acute graft loss. We conclude that the information provided by the B cell crossmatch should be available at the time that a decision to proceed with a renal transplant is made.

Adult↗
PubMed1992

Immunosuppression without prophylactic antilymphocyte preparations.

1. Triple-drug immunosuppression following third party transfusion can result in graft survival equal to protocols that employ prophylactic antilymphocyte preparations. 2. T1/2 was statistically improved in cadaveric and living-related donor grafts in the CsA era. 3. Patients 65 years and older had an excessive death rate. Younger groups were admixed. Extreme youth was not a risk factor. 4. Black recipients had excessive late graft loss. 5. Diabetic recipients had only a slight decline in graft and patient survival rates. 6. First and multiple graft recipients had similar transplant survival rates. 7. Delayed graft function remains costly in this immunosuppressive scheme.

Academic Medical Centers↗
PubMed1991

Intramolecular specificity of anti-HLA alloantibodies.

Recent descriptions of epitopes within HLA class I antigens recognized by mouse monoclonal antibodies are providing an antigenic map of such molecules. However, for transplantation purposes, it is crucial to understand the epitope specificity of alloantibodies. To investigate this issue, we performed sequential absorption/elution studies with serum from a broadly sensitized patient and homozygous typing cells (HTCs) which shared one HLA-A,B antigen with the patient. Antibody reactivity in the different eluates was measured by flow cytometry in a panel of 20 HTCs. These studies revealed two major findings: (a) There were multiple antibodies recognizing one HLA antigen. For example, there were 8 anti-B62 antibodies, 8 anti-B51, 5 anti-B57, 5 anti-B46, and 4 anti-B35. (b) The reactivity of most antibodies correlated highly with the presence of specific amino acids at a given position in the target HLA molecule. Such residues were absent in most HLA antigens not recognized by the antibody. Most of the target residues were located in the accessible alpha helices or connecting loops, but at least one antibody reactivity appeared to be influenced by residues located in the beta sheets. The HLA antigens evaluated in this study were those of the B5, B15, B17 cross-reactive group which have multiple epitopic sites. However, further studies are necessary to determine if alloantibodies directed to other HLA molecules will have a similar or more restricted degree of complexity.

Amino Acid Sequence↗
PubMed1991

HLA epitope matching. Contribution of matched residues to epitopes recognized by alloantibodies.

Applying absorption-elution techniques with homozygous typing cells and flow cytometry, a number of alloantibodies that recognized HLA-B62 but not B46 were identified. B62 and B46 are identical except in amino acids 66-76, which are probably recognized by the B62-specific antibodies. The patients who made these antibodies, however, had HLA antigens sharing amino acids 66-76 with B62, indicating that residues that are identical to the patient's own contribute to the antigenic determinants of foreign HLA molecules. Fine specificity analysis of most of these antibodies revealed that they recognized residues in the 66-76 segment in addition to other residues which were located in close proximity to this segment. We conclude that mismatched amino acid residues located in one part of the HLA molecule can interact with residues that are not different from those in the patient's own HLA molecules to form epitopes recognizable by alloantibodies. These findings should be helpful in improving our understanding of how to use current knowledge at the molecular level for the purpose of matching transplant donors and recipients.

Antibody Specificity↗