Red cell antibody problems in 1000 liver transplants

Liver transplant patients frequently require large amounts of blood. The frequency and nature of their red cell (RBC) antibody problems were examined. Records were reviewed in 496 adults and 286 children undergoing 1000 consecutive transplants. Twenty-two percent of adults and 14 percent of children had RBC alloantibodies. Antibodies of potential clinical significance were found before transplant in 6.3 percent of adults and 1.0 percent of children; despite immunosuppression, they appeared 1 to 5 weeks after transplant in an additional 7.5 and 5.2 percent respectively. These antibodies probably represented secondary immune responses. Of 58 transplant patients with prior potentially significant antibodies, 8 required 7 to 110 units of antigen-untyped blood after 8 to 28 units of antigen-negative blood; of these patients, one had subsequent hemolysis. Positive direct antiglobulin tests in 24 percent of adults and 10 percent of children were most often thought to be due to nonspecific adsorption of IgG. Anti-recipient ABO antibodies developed in 22 of 60 (37%) evaluable ABO-unmatched grafts; 13 cases had associated hemolysis. In all, 36 percent of adults and 20 percent of children had diverse RBC antibody problems. Resolution of these problems is an important part of the laboratory support necessary for a liver transplantation program.     

Vascular remodeling underlies rebleeding in hemophilic arthropathy

Hemophilic arthropathy is a debilitating condition that can develop as a consequence of frequent joint bleeding despite adequate clotting factor replacement. The mechanisms leading to repeated spontaneous bleeding are unknown. We investigated synovial, vascular, stromal, and cartilage changes in response to a single induced hemarthrosis in the FVIII‐deficient mouse. We found soft‐tissue hyperproliferation with marked induction of neoangiogenesis and evolving abnormal vascular architecture. While soft‐tissue changes were rapidly reversible, abnormal vascularity persisted for months and, surprisingly, was also seen in uninjured joints. Vascular changes in FVIII‐deficient mice involved pronounced remodeling with expression of α‐Smooth Muscle Actin (SMA), Endoglin (CD105), and vascular endothelial growth factor, as well as alterations of joint perfusion as determined by in vivo imaging. Vascular architecture changes and pronounced expression of α‐SMA appeared unique to hemophilia, as these were not found in joint tissue obtained from mouse models of rheumatoid arthritis and osteoarthritis and from patients with the same conditions. Evidence that vascular changes in hemophilia were significantly associated with bleeding and joint deterioration was obtained prospectively by dynamic in vivo imaging with musculoskeletal ultrasound and power Doppler of 156 joints (elbows, knees, and ankles) in a cohort of 26 patients with hemophilia at baseline and during painful episodes. These observations support the hypothesis that vascular remodeling contributes significantly to bleed propagation and development of hemophilic arthropathy. Based on these findings, the development of molecular targets for angiogenesis inhibition may be considered in this disease. Am. J. Hematol. 90:1027–1035, 2015. © 2015 Wiley Periodicals, Inc.     

Similar rearrangements of T-cell receptor beta gene in cell lines and uncultured cells from patients with large granular lymphocyte leukemia

We established interleukin-2-(IL-2) dependent cell lines from three patients with large granular lymphocyte (LGL) leukemia. Phenotypic analysis demonstrated retention of the CD3+, CD8+ phenotype that was observed in the original leukemic LGL. Unique rearrangements of T-cell receptor beta gene occurring in uncultured leukemic LGL, were also found in cell lines, which suggests that the cell lines were derived from the original leukemic LGL clone in each case.     

Antibodies to CD40 prevent Epstein-Barr virus-mediated human B-cell lymphomagenesis in severe combined immune deficient mice given human peripheral blood lymphocytes

CD40 is expressed on both normal and neoplastic B lymphocytes. Signal transduction through CD40 in vitro has been shown to exert stimulatory effects on normal B cells and inhibitory effects on Epstein-Barr virus (EBV)-induced B-cell lymphoma lines and some other cell lines derived from patients with aggressive histology lymphoma. The transfer of normal human peripheral blood lymphocytes (huPBL) from EBV-seropositive donors into severe combined immune deficient (SCID) mice has been previously shown to result in the generation of human B-cell lymphomas. These tumors are similar to the highly aggressive EBV-induced lymphomas that can arise clinically after transplantation or in the setting of immunodeficiency. Treatment of huPBL-SCID chimeric mice with anti-CD40 or anti-CD20 monoclonal antibodies (MoAb) significantly delayed the development of EBV-induced B-cell lymphoma. However, the effects of the two MoAb were mechanistically distinct. Anti-CD40 treatment prevented lymphoma generation, while still allowing for functional human B-cell engraftment in the huPBL-SCID mice compared with mice receiving no treatment, all of which succumbed to lymphoma. By contrast, treatment with anti-CD20 significantly inhibited total human B-cell engraftment in the SCID recipients, which accounted for the absence of lymphomas. In vitro assays examining the transformation of human B cells by EBV also indicated that anti-CD40 could directly inhibit EBV- transformation, whereas anti-CD20 antibodies had no effect. Thus, anti- CD40 exerts selective effects to allow for the engraftment of normal human B cells and prevent the emergence of EBV lymphomas. Stimulation of CD40 by antibodies or its physiologic ligand may, therefore, be of significant clinical use in the prevention of EBV-induced B lymphomas that may arise when EBV-seropositive individuals receive immunosuppressive regimens after transplantation or in immune deficiency states, such as acquired immune deficiency syndrome.     

Transforming growth factor-beta potently inhibits the viability- promoting activity of stem cell factor and other cytokines and induces apoptosis of primitive murine hematopoietic progenitor cells

In contrast with the extensively characterized effects of transforming growth factor-beta (TGF-beta) on proliferation and differentiation of hematopoietic progenitors, little is known about the effects of TGF- beta on viability of normal hematopoietic progenitors. In the present report, we demonstrate that TGF-beta potently counteracts hematopoietic growth factor (HGF)-induced survival of individually cultured primitive Lin-Sca-1+ bone marrow progenitors. Specifically, 74% of single Lin-Sca- 1+ cells cultured for 40 hours in the presence of stem cell factor (SCF) survived, whereas only 16% survived in the presence of SCF plus TGF-beta. Similarly, the enhanced survival of primitive hematopoietic progenitors in response to granulocyte colony-stimulating factor (G- CSF), interleukin (IL)-1, IL-6, or IL-11 was also potently opposed by TGF-beta. Furthermore, it is demonstrated that neutralization of endogenous TGF-beta present in the cultures enhances survival of Lin- Sca-1+ progenitors in the absence, as well as in the presence, of HGFs such as SCF and IL-6. The reduced HGF-induced survival of primitive hematopoietic progenitors in the presence of TGF-beta was associated with increased apoptosis, as detected by an in situ terminal deoxynucleotidyl transferase (TdT) assay. After 16 hours of incubation in the absence of HGFs, 61% +/- 6% of the hematopoietic progenitors had DNA strand breaks characteristic of apoptosis. The presence of SCF reduced the frequency of apoptic cells to 27% +/- 5%, whereas 55% +/- 3% of the cells had signs of apoptosis in the presence of SCF plus TGF- beta.     

Localization of 13-hydroxyoctadecadienoic acid and the vitronectin receptor in human endothelial cells and endothelial cell/platelet interactions in vitro

Blood/vessel wall cell interactions depend, in part, on the expression of adhesion receptors on cell surfaces, such as expression of the vitronectin receptor (VnR) on the apical surface of endothelial cells (ECs) for platelet/EC adhesion. However, it is unclear how receptor expression is regulated from within cells. In previous studies, we found that ECs metabolize linoleic acid into the lipoxygenase monohydroxide, 13-hydroxyoctadecadienoic acid (13-HODE), and that the intracellular level of 13-HODE correlates inversely with VnR expression and platelet adhesion to the EC apical surface. In this study, we determined the physical associations of 13-HODE and VnR in unstimulated and stimulated ECs, ie, at times when ECs were and were not adhesive for specific ligands and platelets, using double antibody immunofluorescent staining techniques and binding assays. 13-HODE and the VnR were colocalized within unstimulated ECs. When ECs were stimulated, 13-HODE was no longer detectable, either in or outside the ECs, and the VnR was detected on the apical surface of the ECs. These changes were paralleled by increased vitronectin binding and increased platelet adhesion to the ECs. We suggest that colocalization of 13-HODE with VnR reflects a 13-HODE/VnR interaction, confining the VnR in a nonadhesive form inside unstimulated ECs, and, as a result, the ECs are nonadhesive. When the ECs are stimulated, 13-HODE and VnR dissociate, allowing the VnR to relocate on the EC surface, where the VnR undergoes a conformational change resulting in increased EC adhesivity.     

Human cutaneous T cell lymphoma and leukemia cell lines produce and respond to T cell growth factor

Three cell lines of mature T cell origin derived from patients with cutaneous T cell lymphoma-leukemias (CTCL) were found to be constitutive producers of T cell growth factor (L-TCGF). These are the first reported human cell lines which constitutively produce TCGF. Biologically active TCGF could also be eluted from the surface of these cells using an acid glycine buffer under conditions that maintained cell viability, and subcellular fractionation showed that almost all the TCGF activity was associated with the plasma membrane. Over 30 other human hematopoietic cell lines derived from other disorders were unable to produce TCGF even after induction, and their acid eluates did not contain TCGF activity. L-TCGF from CTCL lines had the same biological activity as TCGF obtained from normal leukocytes (N-TCGF) in that they both supported the long-term growth of normal T cells only after the cells were previously activated by antigen or lectin. Both L-TCGF and N-TCGF increased the rate of proliferation of TCGF-independent and TCGF-dependent CTCL cell lines. The same three factor-independent cell lines that released TCGF adsorbed TCGF in a cell-concentration, time-, and temperature-dependent manner. Since the CTCL cell lines produce TCGF, adsorb TCGF, and increase their proliferative rate in response to TCGF or a related molecule, it is suggested that this endogenously produced factor plays a role in maintaining the abnormal proliferation of these cells in culture as permanently growing cell lines independent of exogenous TCGF. However, this does not mean that this is an essential aspect of neoplastic transformation. Since it is unusual to develop these cell lines in the absence of the continuous need for added TCGF, “autostimulation” may be one of the many unusual variant phenotypic properties sometimes associated with neoplastic cells that gives them a selective advantage for in vitro growth.