High-sensitivity cardiac troponin I assay to screen for acute rejection in patients with heart transplant.

Background: A noninvasive biomarker that could accurately diagnose acute rejection (AR) in heart transplant recipients could obviate the need for surveillance endomyocardial biopsies. We assessed the performance metrics of a novel high-sensitivity cardiac troponin I (cTnI) assay for this purpose.

Methods And Results: Stored serum samples were retrospectively matched to endomyocardial biopsies in 98 cardiac transplant recipients, who survived ≥3 months after transplant.

Alleles of keratin 1 in families and populations.

Keratin 1 is found in the upper layers of the epidermis, on the surface of endothelial cells and in the membrane of the neuroblastoma NMB7. It is important for the structural integrity of the skin, has been found to regulate the activity of kinases, such as protein kinase C (PKC) and SRC, to participate in complement activation by the lectin pathway and to be involved in fibrinolysis, angiogenesis and the response to oxidative stress. Studies of the polymorphisms of the Keratin 1 (KRT1) gene have been driven mostly by interest in its role in skin diseases.

Identification of endothelial cell surface antigens encoded by genes other than HLA. A combined immunoprecipitation and proteomic approach for the identification of antigens recognized by antibodies against endothelial cells in transplant recipients.

It has been known for some time that transplant recipients may have antibodies to endothelial cells which are not detected on lymphocytes. However, little progress has been made in the analysis of these endothelial antigens. In the present experiments we have attempted to characterize endothelial cell surface antigens to which antibodies were produced during graft rejection.

Antibodies against nucleolin in recipients of organ transplants.

Background: Patients who reject allografts frequently make strong antibody responses against donor human leukocyte antigens and autoantigens such as vimentin, collagen V, or alpha-tubulin and it has been postulated that autoantibodies may play a role in allograft failure.

Methods: We have used serum from patients who recently rejected an allograft as a source of antibodies in combination with lysates of human umbilical vein endothelial cells as a source of target antigens. Immunoprecipitation and protein identification was performed by mass spectrometry.

Evaluation of the highly sensitized transplant recipient.

The immune response against alloantigens involves the production of antibodies and development of T-cell immunity. Recipients sensitized to HLA antigens may have antibodies to almost all donors and may not be able to find a suitable kidney transplant donor. Strategies available to enable these patients to obtain a transplant are to give priority to highly sensitized patients, to perform therapy for antibody reduction or to transplant with existing antibodies and to intervene as needed with post-transplant treatment.

Bridge to heart transplantation with left ventricular assist device versus inotropic agents in status 1 patients.

Objective: Left ventricular assist devices (LVADs) are commonly used for critically ill patients awaiting heart transplantation, although their effect on long-term outcomes, relative to inotropic support alone, is still debated.

Method: Data from Status 1 patients who underwent heart transplantation at our institution between 1990 and 2005 were reviewed (n = 180). They were divided into two groups: those who underwent LVAD implantation as a bridge to transplant (n = 31) and those treated with inotropic agents without the support of LVAD (n = 149).

Utility of routine immunofluorescence staining for C4d in cardiac transplant recipients.

Background: Immunofluorescence staining of endomyocardial biopsy (EMB) specimens to detect the complement fragment C4d is used to diagnose antibody-mediated rejection. However, data are limited regarding the utility of routine staining for C4d in clinical care.

Methods: This study retrospectively reviewed the clinical course of adult cardiac transplant recipients who underwent > or = 2 EMBs with immunofluorescence C4d staining at the University of Texas Southwestern Medical Center since September 2006.

Role of immunoglobulin (Ig)-G and IgM antibodies against donor human leukocyte antigens in organ transplant recipients.

Antibodies against HLA antigens offer a window to the response of transplant recipients to the challenge of allografts. HLA alleles produced by recombinant technology and attached to color-coded polystyrene microspheres are now in widespread use. They offer antibody detection by flow cytometry at a high level of sensitivity.

Successful renal re-transplantation in the presence of pre-existing anti-DQ5 antibodies when there was zero mismatch at class I human leukocyte antigen A, B, & C: a case report.

Introduction: Hyperacute rejection may be prevented by avoiding the transplantation of kidneys into patients with pre-existing anti-donor Class I human leukocyte antigen antibodies. However, the role of anti-donor-Class II-human leukocyte antigen-DQ antibodies is not established. The question is ever more relevant as more sensitive cross-matching techniques detect many additional antibodies during the final crossmatch.

Peripheral blood B cells producing donor-specific HLA antibodies in vitro.

Donor-specific HLA antibodies have been associated with acute and chronic rejection. Such antibodies may sometimes not be detected in recipient serum. In an attempt to learn about possible mechanisms, we investigated antibody production by recipient B lymphocytes in vitro.

The emerging issue of MICA antibodies: antibodies to MICA and other antigens of endothelial cells.

The major histocompatibility complex (MHC) encodes the HLA class I antigens expressed on the surface of most nucleated cells and the HLA class II antigens which are expressed mostly in B lymphocytes, monocytes and dendritic cells. Mismatched HLA antigens are the main source of the immune response that leads to the rejection of allografts. In some patients however, rejection may occur without a detectable response to donor HLA antigens.

Antibodies against donor human leukocyte antigens and the outcome of cardiac allografts in adults and children.

Background: Mismatched histocompatibility antigens between donor organ and host stimulate the immune response that causes allograft rejection. Antibodies against human leukocyte antigen (HLA) are known to appear in the serum of heart transplant recipients.

Methods: We have tested stored sera with HLA bound to polystyrene microbeads in a retrospective analysis of heart recipients transplanted in our center to better understand the impact of antibodies against HLA on the posttransplant course.

Detection of anti-MICA antibodies in patients awaiting kidney transplantation, during the post-transplant course, and in eluates from rejected kidney allografts by Luminex flow cytometry.

Previously we have reported on the development of antibodies against MICA alleles in kidney transplant recipients. These alloantibodies have now been determined using a new assay using Luminex beads bound to soluble recombinant MICA antigens produced in insect cells. In the present study we have analyzed sera from 85 kidney transplant recipients on the waiting list and 66 patients transplanted within the last 4 years and 59 acid eluates obtained from allograft nephrectomy specimens.

Study of MICA alleles in 201 African Americans by multiplexed single nucleotide extension (MSNE) typing.

We have developed a method for major histocompatibility complex class I chain-related gene A (MICA) genotyping using multiplexed single nucleotide extension (MSNE) and flow cytometric analysis of an array of fluorescent microspheres. This technique employs a polymerase chain reaction-derived target DNA containing all the polymorphic sites of MICA, synthetic complementary primers, biotinylated dideoxynucleotide triphosphate, fluorescent reporter molecules (streptavidin-phycoerythrin), and thermophilic DNA polymerase. Genomic DNA was amplified by MICA locus-specific primers and the MSNE reactions were carried out in the presence of 30 MSNE primers used to assay polymorphisms in exons 2, 3, and 4 of the MICA genes.

MICA is a target for complement-dependent cytotoxicity with mouse monoclonal antibodies and human alloantibodies.

The highly polymorphic major histocompatibility class I related chain A (MICA) gene encodes glycoproteins that have been shown to be expressed in epithelial cells, endothelial cells, keratinocytes, monocytes, and tumor cells. In previous experiments, we have studied MICA antigens using rabbit sera obtained by immunization with MICA peptides. We also found that several transplant recipients had specific antibodies against MICA in an ELISA assay with recombinant of MICA (r-MICA).

MICA polymorphism in South American Indians.

We have studied the MICA alleles of 196 unrelated subjects from three South American Indian tribes (Toba, Wichi and Terena). They are members of isolated tribes located in the Gran Chaco area in northeastern Argentina and in Mato Grosso do Sul in South Central Brazil. Of 55 previously known alleles, nine were observed in South American Indians, compared with 16 that were found in North American Caucasians, suggesting a more restricted allelic distribution of MICA in these tribes.