Identification of human erythrocyte blood group antigens on decay-accelerating factor (DAF) and an erythrocyte phenotype negative for DAF.

Decay accelerating factor (DAF) is a glycoprotein present on the surfaces of many types ofcells in contact with plasma, including erythrocytes, leukocytes, and platelets (reviewed in reference 1). A small amount of DAF is also present in serum. Numerous investigators have demonstrated that DAF inhibits the action of C3 convertases on cell surfaces, and its absence has been shown to be at least partially responsible for the abnormal sensitivity to lysis by complement exhibited by erythrocytes of patients with the acquired stem cell disorder paroxysmal nocturnal hemoglobinuria (PNH) (2). Hereditary absence of DAF has not been previously described. Tc(a) and Cr(a) are high-frequency human erythrocyte antigens . These antigens are part of a family of blood group antigens, designated Cromer related, which are all absent from the null phenotype cell IFC(-) , or Inab (3). Recently, Spring and colleagues (4) have identified two monoclonal antibodies which bound to high frequency red cell antigens absent from the Inab phenotype. They also demonstrated that these antibodies, as well as several human antisera to Cromer-related antigens, bound to a 70-kD glycoprotein when used to stain immunoblots of human erythrocyte membrane proteins . Because the wide tissue distribution of mAb reactivity, along with some of the biochemical characterization and immunoblotting data, was similar to that of DAF, we investigated whether the Cromer-related antigens Cr(a) and Tc(a) resided on the DAF molecule.

Role and regulation of sickle red cell interactions with other cells: ICAM-4 and other adhesion receptors.

Erythrocytes containing primarily hemoglobin S (SS RBCs) are abnormally adherent. We now know that SS RBCs express numerous adhesion molecules, and that many of these can undergo activation. SS RBCs exposed briefly to epinephrine show markedly increased adhesion to both laminin and endothelial cells. In vivo, infusion of epinephrine-activated but not unstimulated SS RBCs causes RBC adhesion, vaso-occlusion, organ trapping, and shortened RBC survival in the circulation. Epinephrine treatment of SS RBCs before infusion also induces adhesion of murine leukocytes to vascular walls. Indeed, in vitro, SS RBCs can activate leukocyte adhesion and cytokine production. We now have demonstrated both in vitro and in vivo evidence for the importance of RBC signaling and have also shown that SS RBC adhesion is determined by genetic polymorphisms in the signaling pathway that activates adhesion. These advances will hopefully lead to new therapeutic modalities for sickle cell disease.

Human erythrocyte antigens. Regulation of expression of a novel erythrocyte surface antigen by the inhibitor Lutheran In(Lu) gene.

Our study describes a novel human erythrocyte protein antigen, the expression of which is regulated by the rare Lutheran inhibitor In(Lu) gene. We have produced a monoclonal antibody (A3D8) that bound strongly to erythrocytes from subjects with Lutheran phenotypes Lu(a+b+), Lu(a+b-), and Lu(a-b+) but bound negligibly to erythrocytes from subjects with the dominant form of Lu(a-b-) phenotype, reflecting inheritance of the In(Lu) gene. Importantly, erythrocytes from an individual with the recessive form of Lu(a-b-) phenotype (i.e., absence of the In(Lu) gene and absence of genes encoding for Lutheran antigens) showed reactivity with A3D8 antibody comparable to that seen with Lu(a+) or Lu(b+) erythrocytes. A3D8 antigen activity was also found on all leukocytes and in serum and plasma; this activity also appeared to be regulated by the In(Lu) gene in serum, plasma, and on a subset of leukocytes. Thus, we have identified a human erythrocyte protein whose expression is modified by the In(Lu) gene. This knowledge that such an antigen exists on erythrocytes and in normal plasma should allow further studies into the molecular genetics of the In(Lu) gene and into the functional and structural significance of the A3D8 antigen.

Increased efficiency of binding of nascent C3b to the erythrocytes of chronic cold agglutinin disease.

The pathogenesis of chronic cold agglutinin disease (CCAD) has been enigmatic. To determine if abnormal erythrocyte membrane constituents might provide the stimulus for antibody production, we compared the electrophoretic pattern of radiolabeled membrane glycoproteins of four patients with CCAD to that of normal control erythrocytes. For the CCAD erythrocytes, fluorographs revealed the appearance of an abnormal band whose molecular weight was estimated at 126,000 D. Using two-dimensional gel analysis and immunoblotting techniques, it was determined that the 126,000 D glycoprotein consisted predominately of polymeric glycophorin-alpha. Previous investigations had suggested that abnormalities in glycophorin-alpha influence the functional activity of the complement system. When purified complement (C)3 was activated in the fluid-phase by cobra venom factor complexes, CCAD erythrocytes bound nascent C3b 7-27 times more efficiently than normal erythrocytes. Normal erythrocytes could be induced to manifest the appearance of the 126,000 D band, and the increased efficiency of binding of nascent C3b by incubation with CCAD serum or with the purified cold agglutinin antibody plus autologous serum, but not with the purified antibody alone or the purified antibody plus EDTA-chelated autologous serum. These studies demonstrate that the interactions of IgM cold-reacting antibody and complement with glycophorin induce changes in the biophysical properties of the erythrocyte membrane which modify subsequent interactions with complement.

Dr(a-) polymorphism of decay accelerating factor. Biochemical, functional, and molecular characterization and production of allele-specific transfectants.

The Dra antigen belongs to the Cromer-related blood group system, a series of antigens on decay accelerating factor (DAF), a glycosyl-phosphatidylinositol-anchored membrane protein that protects host cells from complement-mediated damage. We studied the rare inherited Dr(a-) phenotype to ascertain the associated biochemical and functional changes in DAF and to characterize the basis for this polymorphism. Radioimmunoassay assay and flow cytometric analysis of Dr(a-) erythrocytes demonstrated 40% of normal surface expression of DAF but normal levels of several other glycosyl-phosphatidylinositol-anchored proteins, distinguishing this phenotype from that of paroxysmal nocturnal hemoglobinuria. Western blots confirmed this reduced DAF expression and indicated a slightly faster mobility of the molecule on SDS-PAGE. Despite the reduced DAF expression, Dr(a-) erythrocytes functioned normally in the complement lysis sensitivity assay. Utilization of the polymerase chain reaction to amplify mononuclear cell genomic DNA from three unrelated Dr(a-) individuals demonstrated that a point mutation underlies the Dr(a-) phenotype: a C to T change in nucleotide 649 resulting in a serine165 to leucine change. This defines the Drb allele of DAF, which can be distinguished from Dra by a Taq I restriction fragment length polymorphism. We created transfected Chinese hamster ovary cell lines expressing either the Dra or the Drb allelic form of DAF. These allele-specific transfectants were tested by inhibition of hemagglutination or flow cytometry and confirmed the specificity of anti-Dra alloantisera. The allele-specific transfectants could form the basis of a new serological approach to immunohematology.

Basal cell adhesion molecule/lutheran protein. The receptor critical for sickle cell adhesion to laminin.

Sickle red cells bind significant amounts of soluble laminin, whereas normal red cells do not. Solid phase assays demonstrate that B-CAM/LU binds laminin on intact sickle red cells and that red cell B-CAM/LU binds immobilized laminin, whereas another putative laminin binding protein, CD44, does not. Ligand blots also identify B-CAM/LU as the only erythrocyte membrane protein(s) that binds laminin. Finally, transfection of murine erythroleukemia cells with human B-CAM cDNA induces binding of both soluble and immobilized laminin. Thus, B-CAM/LU appears to be the major laminin-binding protein of sickle red cells. Previously reported overexpression of B-CAM/LU by epithelial cancer cells suggests that this protein may also serve as a laminin receptor in malignant tumors.

Lack of isohemagglutinin production following minor ABO incompatible unrelated HLA mismatched umbilical cord blood transplantation.

While immune hemolysis due to donor isohemagglutinin (IH) production often complicates minor ABO incompatible peripheral blood hematopoietic stem cell transplantation (PBSCT), it is not known if this occurs with umbilical cord blood transplantation (UCBT). We compared IH production and hemolysis following minor ABO allogeneic PBSCT and UCBT. We reviewed 24 ABO minor incompatible allogeneic PBSCTs and 14 ABO minor incompatible UCBTs. Patients were evaluated for donor-derived IH by reverse ABO grouping. Evaluation of hemolysis was based on clinical and laboratory findings of anemia associated with increased RBC transfusion need, concomitant with the appearance of donor-derived IH. Of the 24 ABO minor incompatible allogeneic PBSCTs, 15 produced donor-derived IH from 6 to 88 days following transplantation, with seven of 15 patients exhibiting clinically evident hemolysis. There was no significant difference in days to leukocyte engraftment or infused CD34 cells in patients with or without donor-derived IH. None of the 14 patients receiving ABO incompatible UCBTs showed evidence of donor-derived IH following transplantation with a median follow-up of 60 days. We conclude that donor IHs are not produced in patients undergoing minor ABO incompatible UCBTs suggesting fundamental immunologic differences between allogeneic PBSCT and UCBT.

LW protein: a promiscuous integrin receptor activated by adrenergic signaling.

The LW blood group antigen glycoprotein, although part of the Rh macromolecular complex, is nonetheless a member of the intercellular adhesion molecule (ICAM) family. Thus, while it is only rarely clinically important in the setting of transfusion and pregnancy, LW is likely to contribute to red cell adhesion in a variety of settings, including during hematopoiesis, as well as in vascular disorders. The best documentation of a pathophysiological role for LW in human disease is in sickle cell disease, where it contributes to red cell adhesion to endothelial cells and the development of vaso-occlusion, the hallmark of that disease. LW may also contribute to other intravascular processes, such as both venous and arterial thrombosis, due to its ability to interact with both activated platelets as well as leukocytes. The evidence that LW itself can undergo activation on red cells holds promise that pharmacotherapeutic maneuvers may be found to prevent such pathophysiologic interactions.

Principles and problems of transfusion in sickle cell disease.

Sickle cell disease (SCD) is associated with red blood cell (RBC) abnormalities and moderate to severe anemia, and blood transfusion is naturally a mainstay of treatment. However, transfusion therapy for SCD may incur special and distinctive adverse effects. Thus, it is important to understand the indications for and goals of transfusion therapy and to be aware of the potential side effects of therapy. Years of unsystematic clinical observations, followed by more carefully designed and in some cases randomized studies, have contributed substantially to our knowledge of transfusion therapy in SCD. However, much remains unknown and areas of controversy persist. In addition, serologic barriers pose enduring roadblocks to the optimization of transfusion therapy for patients with SCD, and the syndrome of massive hemolytic transfusion reactions and hyperhemolysis in SCD persists as a life-threatening complication for which appropriate clinical management is not yet defined.

Red blood cell surface adhesion molecules: their possible roles in normal human physiology and disease.

Human erythrocytes express a relatively large number of known adhesion receptors, despite the fact that red blood cells (RBCs) are generally considered to be nonadhesive for endothelial cell surfaces. Some of these adhesion receptors are expressed by many other tissues, while others have more limited tissue distribution. Some adhesion receptors, including CD36 and VLA-4, are only expressed by immature erythroid cells, while others are present on mature erythrocytes. The structure and function of these proteins is reviewed here. LW, CD36, CD58, and CD147 have been shown in other tissues to mediate cell-cell interaction. Other receptors, such as CD44, VLA-4, and B-CAM/LU, can mediate adhesion to components of extracellular matrix. In addition, their roles in normal erythropolesis, as well as in the pathophysiology of human disease, are summarized. The most convincing evidence for a pathophysiologic role for any of these receptors on erythrocytes comes from studies of cells from patients homozygous for hemoglobin S, as RBC adhesion is thought to contribute to vaso-occlusion. Thus, receptors such as B-CAM/LU may become targets for future therapy aimed at preventing or ameliorating this thrombotic process.

HIV-associated autoimmune hemolytic anemia: report of a case and review of the literature.

While anemia and a positive direct anti-globulin test are each frequently observed in the clinical syndrome of human immunodeficiency virus (HIV) infection, autoimmune hemolytic anemia has rarely been reported in this setting. A case of severe warm autoimmune hemolytic anemia (AIHA) with reticulocytopenia in a patient with AIDS-related complex is reported. Laboratory and clinical findings of severe hemolysis were present, including anhaptoglobinemia, microspherocytosis, splenomegaly, and transfusion dependence. Azidothymidine (AZT) therapy may have exacerbated this patient's anemia. Splenectomy produced a delayed but complete remission of the AIHA despite continuation of AZT therapy. Review of other reports of positive direct antiglobulin tests and autoimmune hemolytic anemia in patients with HIV infections suggests that autoantibodies may be a significant cause of anemia in this population and that the frequent lack of reticulocytosis, despite bone marrow erythroid hyperplasia, may lead to the underdiagnosis of AIHA in HIV-infected patients.

Human medullary thymocyte p80 antigen and In(Lu)-related p80 antigen reside on the same protein.

Study of human T lymphocyte differentiation antigens with monoclonal antibodies has led to the identification of two antigens shared by erythrocytes and leukocytes. The protein (p80) defined by A1G3 antibody has previously been shown to be acquired during human intrathymic T-cell maturation. The antigen defined by A3D8 antibody has been demonstrated also to reside on an 80 kd protein; expression of the A3D8 antigen on erythrocytes and a subset of leukocytes is regulated by the rare In(Lu) gene. In this study, we demonstrate that the antigens defined by the A1G3 and A3D8 antibodies reside on the same protein and represent closely related but nonidentical epitopes on the p80 molecule. Expression of the A1G3 antigen on erythrocytes and a subset of leukocytes is also down-regulated by the In(Lu) gene. The possible role of the In(Lu) gene in thymocyte differentiation is discussed.

Expression of the cell adhesion molecule CD44 in gastric adenocarcinomas.

CD44, an integral membrane glycoprotein expressed by many cell types, serves as the principal transmembrane hyaluronate receptor and may be a determinant of metastatic and invasive behavior in carcinomas. The expression of CD44 in 23 gastric adenocarcinoma and 12 peptic ulcer disease (PUD) resection specimens and gastric carcinoma cell lines HS746t and KATO III was examined by immunohistochemistry using the murine monoclonal antibody A3D8 on formalin-fixed, paraffin-embedded tissue or cells. Western blot analysis of whole cell lysates of KATO III and HS746t cells showed protein bands at 85 to 90 kd with KATO III cells expressing an additional band at 145 kd. In normal stomach gastric epithelium was negative. In PUD foveolar epithelium was focally positive, but staining did not correlate with the extent of gastritis. In carcinoma cases intensity of staining was progressively stronger comparing intestinal metaplasia with dysplasia with intramucosal carcinoma. Invasive carcinoma was invariably more strongly positive than dysplasia or intramucosal carcinoma. Twelve adenocarcinomas were weakly positive and 11 were strongly positive. The staining intensity of metastases (12 cases) was the same or weaker than the primary tumor. For the 12 patients whose carcinomas were weakly positive, mean length of survival for the six who died was 23.3 months. Five of the 11 patients whose carcinomas strongly expressed CD44 died within the study period with a mean length of survival of 11.0 months. A key consequence of CD44 overexpression in gastric carcinomas may be development of the invasive phenotype and strong expression may indicate a poorer prognosis.

Cardiac metastasis from a transitional cell carcinoma: a case report.

We report the case of a patient with a metastatic tumor in the right ventricle, apparently derived from a transitional cell carcinoma. The patient presented with severe hypoxemia as a result of right-to-left shunt due to the position of the tumor and a patent foramen ovale. The clinical course of this case is presented and the pathophysiology of the physiological effects caused by the metastatic tumor is discussed. The literature concerning cardiac metastases is reviewed.

Phosphatidylinositol-linked red blood cell membrane proteins and blood group antigens.

A new class of membrane proteins has recently been described. Unlike integral membrane proteins, which traverse the membrane with one or more hydrophobic peptide domains, the peptide domains of these more newly described proteins are entirely extracellular and are anchored to the cell membrane via a phosphatidylinositol-glycan (GPI) anchor. Erythrocyte membrane proteins of this class include proteins with diverse functions; several, however, are complement regulatory proteins. Moreover, it is the lack of expression of GPI-anchored proteins that is responsible for manifestations of the acquired hematologic disease paroxysmal nocturnal hemoglobinuria. Recently, several investigators have also demonstrated that a number of erythrocyte blood group antigens reside on this class of proteins. These antigens include those of the Cromer blood group, JMH, Holley/Gregory, Cartwright, and Dombrock. The biochemical basis for the Cromer, JMH, and Holley/Gregory antigens have so far been partly delineated.

Large-scale use of red blood cell units containing alloantibodies.

Many transfusion services are reluctant to accept red blood cell (RBC) units containing antibodies. We evaluated the impact of accepting routine shipments of our region's inventory of alloantibody- positive RBC units over a 4-month period. All patients' samples received up to 30 days after transfusion of such units were evaluated for the presence of passively acquired antibody, and labor and reagent costs were determined. During the study period, we received 259 alloantibody-containing RBC units, and 253 of these were transfused to 187 patients. Follow-up samples were received on 99 of these 187 patients, and 10 of these patients had detectable passive antibody in posttransfusion antibody screening tests. Two patients had anti-C and -D and eight patients had anti-D. Due to our negotiation of a small discount for antibody-containing units and the use of 20 units based on labeled phenotype rather than antigen typing in our laboratory, we experienced a net savings of $3814 over the 4-month period. This savings was achieved despite some additional costs incurred, including costs of data entry and additional testing on patients' samples. We concluded that large-scale use of RBC units from donors with alloantibodies is safe and likely to have a minimal impact on a busy transfusion service's workload and costs. Furthermore, nationwide use of such units would help alleviate projected blood shortages.

Identification of the Tcb allele of the Cromer blood group gene by PCR and RFLP analysis.

The Cromer blood group antigens reside on the complement regulatory protein, decay-accelerating factor (DAF). The Cromer system comprises 10 antigens, 3 of which are of low incidence. When an individual is homozygous for the allele encoding one of these low-incidence antigens, they are liable to produce an antibody to the antithetical high-frequency antigen if challenged by pregnancy or transfusion. These antibodies are often difficult to identify, because of the lack of readily available antigen-negative cells and typing sera. In blacks, about 5 percent of individuals carry the rare Tcb Cromer allele. We have shown that the presence of the low-incidence Tcb allele can be detected by polymerase chain reaction (PCR) amplification of a fragment of the gene encoding DAF, followed by allele-specific restriction enzyme digestion.

A case report: IgG autoanti-N as a cause of severe autoimmune hemolytic anemia.

A 21-year-old white worn was referred for evaluation of hemolytic anemia after a 9-day history of marked hemoglobinuria, jaundice, and weakness. The patient's hematocrit was 18%, despite at least eight transfusions over the previous week, and the reticulocyte count was < 1%. Serologic evaluation revealed a weakly positive direct antiglobulin test with anti-C3 only The serum contained cold and warm-reacting anti-N Dithiothreitol had no effect on either the cold- or the warm-reacting anti-N activity, and radioimmunoassay with monoclonal anti-IgG was strongly positive, indicating that both the cold- and the warm-reacting anti-N reactivity resided in the IgG fraction. The patient was treated with N - 'N' + red cell transfusions, prednisone, and azathioprine and gradually became transfusion independent. Postrecovery typing revealed her red cells to be M+N+S+s+. This constitutes the third case of autoimmune hemolytic anemia associated with IgG autoanti-N. The marked hemoglobinuria and reticulocytopenia are unique features of this case.

Glycosyl phosphatidylinositol-linked blood group antigens and paroxysmal nocturnal hemoglobinuria.

Human erythrocyte cell surface molecules that are attached to the cell membrane by glycosyl-phosphatidylinositol (GPI) anchors include the complement regulatory proteins decay accelerating factor (DAF, CD55) and membrane inhibitor of reactive lysis (MIRL, CD59), as well as the proteins that bear the Cartwright, Dombrock, and JMH blood group antigens. The acquired hematopoietic stem cell disorder paroxysmal nocturnal hemoglobinuria (PNH) results from the absence or marked deficiency in expression of GPI-anchored proteins in affected hematopoietic cells. PNH usually if not always results from a somatic mutation of an X-linked gene called PIG-A; the product of the PIG-A gene is a glycosyl transferase necessary for construction of the GPI anchor. DAF is a ubiquitously expressed protein present in many tissues, including gastrointestinal epithelia, corneal epithelia, and serosa of urinary and reproductive organs. DAF is a 70 kD glycoprotein containing complement regulatory short consensus repeats (SCRs); its gene is located in the regulation of complement activation (RCA) gene cluster on chromosome 1 and is about 40 kb in size. The Cromer blood group antigens, which reside on DAF, include 10 currently defined antigens, of which seven are of high incidence. The molecular basis of the Cr (a-) phenotype has been determined to be a single base pair substitution in DAF SCR4 (G-->C, leading to an ala193 to pro amino acid substitution). The Tc alpha antigen appears to be determined by the amino acid sequence of SCR1, with the Tc (a-b+) phenotype arising from a base pair substitution of G55-->T, leading to an arg18 to leu amino acid substitution. The null phenotype for Cromer antigens occurs when DAF is completely absent; only one example has been completely studied on the molecular level. That individual is homozygous for a point mutation in SCR1 (G314-->A) that creates a stop codon (TGA) in place of one normally encoding trp53 (TGG) and thus prevents further translation of the mRNA. The Dr(a-) phenotype expresses reduced quantities of DAF (approximately 40% of normal levels), as well as a polymorphism of DAF. Lack of the Dr alpha antigen has been proved to result from a single point mutation in SCR3 (C-->T in codon 165) that leads to a single amino acid substitution (ser-->leu). The Cartwright (Yt) antigens reside on acetylcholinesterase (AChE). In erythroid cells, a small exon that encodes the signal for attachment of the GPI anchor is retained in a tissue-specific process.(ABSTRACT TRUNCATED AT 400 WORDS)

Lutheran antigens, CD44-related antigens, and Lutheran regulatory genes.

The Lutheran (Lu) blood group antigens are a family of human erythrocyte antigens which reside on two closely-related erythrocyte integral membrane proteins. Sixteen Lutheran or so-called para-Lutheran antigens have thus far been described, and human antisera to many of them have been shown to immunoblot two proteins, of 78 and 85 kDa. Lu cDNA encodes an integral membrane protein of 597 amino acids that is a member of the Ig superfamily. Lu proteins comprise five Ig superfamily domains, along with a single transmembrane domain and a cytoplasmic domain of about 60 amino acids. The two proteins seen in biochemical studies of red cell membranes appear to be derived from 2 mRNA species that differ only in their 3' ends, suggesting that they arise from alternate splicing of a single preRNA. Three genetic backgrounds for the Lu(a-b-) [Lu null] phenotype have been described. A recessive Lu null phenotype is rarely observed as a result of homozygosity for two amorphic LU alleles. However, the most common Lu(a-b-) phenotype appears to be caused by an independently segregating, dominant gene, designated In (Lu), which inhibits expression of all Lutheran antigens to nearly undetectable levels. This gene also affects the expression of other cell surface proteins and blood group antigens that are genetically unlinked to the Lutheran locus, including CD44 and MER2. CD44, a member of the cartilage link family of proteins, bears the In and AnWj blood group antigens. A widely distributed protein CD44 is expressed at normal levels on all tissues except erythrocytes in the presence of the In (Lu) gene. A second Lutheran regulatory gene, XS2, is responsible for the third Lu(a-b-) phenotype, which exhibits an X-linked inheritance pattern. The XS2 gene down-regulates but does not abolish expression of LU genes and does not affect expression of CD44.