Identity of the Epstein-Barr virus (EBV) receptor with the complement receptor type 2 (CR2) was established in three sets of experiments using the monoclonal antibodies, HB-5 and anti-B2, which recognize a Mr 145,000 Blymphocyte membrane protein that is CR2. First, the rank order for binding of fluoresceinated EBV to four lymphoblastoid cell lines (SB, JY, Raji, and Molt-4) was identical to the rank order for binding of HB-5 and anti-B2 by analytical flow cytometry. Second, pretreatment of cells with HB-5 followed by treatment with goat F(ab')2 fragments to mouse IgG blocked binding of fluoresceinated EBV on SB, a B-lymphoblastoid cell line. Virus attachment was not inhibited by alone, second antibody alone, rabbit anti-C3b receptor, or UPC10 (an irrelevant monoclonal antibody). Third, transfer of CR2 from SB to protein A-bearing Staphylococcus aureus particles, to which HB-5 had been absorbed, conferred on them the specific ability to bind 1251-labeled EBV. We conclude that CR2 is the EBV receptor of human B lymphocytes.pressed on phagocytes and large granular lymphocytes having natural killer and antibody-dependent cytotoxic activities, but it is not expressed on B lymphocytes (18-21). It consists of two polypeptide chains of Mr 155,000-185,000 and Mr 95,000-105,000 (20,22,23). The C3d receptor or CR2 binds the C3d region of C3d,g, iC3b and, with less affinity, C3b. It is found on mature B lymphocytes and on certain Bcell lines (24-29). It has been characterized as a Mr 140,000-145,000 membrane protein (26,27) that is recognized by the monoclonal antibodies (mAbs) termed anti-B2 (28) and , respectively.In the present study, these mAbs have been used to show that the EBVR and CR2 are quantitatively coexpressed on four cell lines, that binding of antibody to CR2 can prevent attachment of EBV, and that CR2 that has been immunoabsorbed onto particles of Staphylococcus aureus Cowan I strain (SACI) specifically binds EBV.

DNA base sequence comparisons demonstrate that the principal family of 300-nucleotide interspersed human DNA'sequences, the repetitive double-strand regions of HeLa cell heterogeneous nuclear RNA, and specific RNA polymerase III in vitro transcripts of cloned human DNA sequences are all representatives of a closely related family of sequences. A segment of approximately 30 residues of these sequences is highly conserved in mammalian evolution because it is also present in the interspersed repeated DNA sequences of Chinese hamsters. Further DNA sequence comparisons demonstrate that a portion of this highly conserved segment of repetitive mammalian DNA sequence is similar to a sequence found within a low molecular weight RNA that hydrogen-bonds' to poly(A) terminated RNA molecules of Chinese hamsters and a sequence that forms half of a perfect inverted repeat near the origin of DNA replication in papovaviruses.

HLA-F is currently the most enigmatic of the human MHC-encoded class Ib genes. We have investigated the expression of HLA-F using a specific Ab raised against a synthetic peptide corresponding to amino acids 61–84 in the α1 domain of the predicted HLA-F protein. HLA-F is expressed as a β2-microglobulin-associated, 42-kDa protein that shows a restricted tissue distribution. To date, we have detected this product only in peripheral blood B cells, B cell lines, and tissues containing B cells, in particular adult tonsil and fetal liver, a major site of B cell development. Thermostability assays suggest that HLA-F is expressed as an empty heterodimer devoid of peptide. Consistent with this, studies using endoglycosidase-H and cell surface immunoprecipitations also indicate that the overwhelming majority of HLA-F contains an immature oligosaccharide component and is expressed inside the cell. We have found that IFN-γ treatment induces expression of HLA-F mRNA and HLA-F protein, but that this does not result in concomitant cell surface expression. HLA-F associates with at least two components of the conventional class I assembly pathway, calreticulin and TAP. The unusual characteristics of the predicted peptide-binding groove together with the predominantly intracellular localization raise the possibility that HLA-F may be capable of binding only a restricted set of peptides.

The human 3 globin gene encodes the ,3 globin chain of normal adult hemoglobin A (subunit structure a2(2). A large number of genetic disorders of the ,3 globin gene are known: hemoglobinopathies, characterized by synthesis of qualitatively abnormal ( globin chains, and the f3-thalassemias, characterized by quantitatively deficient synthesis of (3 globin chains.The /3-thalassemias are a clinically and biochemically heterogeneous group of disorders, which probably result from a wide variety of molecular defects. In 3+-thalassemia, the most common type of 03-thalassemia, /3 globin chain synthesis is decreased to approximately 5-30% ofnormal in the erythroid cells of affected individuals (1, 2). Those 3 chains that are produced appear normal by both carboxymethylcellulose column chromatography and peptide analysis (reviewed in ref.3). Moreover, there is a corresponding deficiency of P globin mRNA in (8+-thalassemic erythroid cells (4-6). This mRNA also appears normal by cDNA-RNA hybridization criteria and by its ability to direct translation ofnormal ,3 globin chains in vitro (2). These features suggest that the l3+-thalassemias may result from abnormalities of ( globin gene transcription or of processing, transport, or stability of /3 globin mRNA. Apparent abnormal processing or instability of nuclear /3 globin mRNA precursor molecules has been observed in some cases (7-10).Family studies have indicated that most /3-thalassemia mutations are allelic with, or tightly linked to, the ,B globin structural locus (1, 2), suggesting that structural analysis of thalassemic /3 globin genes might yield insight into the molecular basis of these disorders. Accordingly, we have cloned , globin gene fragments from a patient with /3+-thalassemia, and we have determined the complete nucleotide sequence of this thalassemic 3 globin gene. Comparison with the nucleotide sequence of a normal human f3 globin gene (11) reveals only a single divergent nucleotide, which occurs in the internal region of the small intervening sequence. This sequence difference suggests a possible mechanism for abnormal splicing of the thalassemic nuclear P3 globin mRNA precursor. MATERIALS AND METHODSMolecular Cloning. Total DNA was prepared from the spleen of a 12-year-old Greek Cypriot girl with typical transfusion-dependent 83+-thalassemia. The f3/a globin chain synthetic ratio obtained after incubation ofher ervthroid cells with [3H]leucine was 0. 14. The erythrocytes ofboth her parents had elevated Hb A2 levels of4.2% and 4.9%, respectively, as well as hypochromia and microcytosis, characteristic of heterozygous thalassemia; the Hb F values in the parents' erythrocytes were 1.3% and 1.7%, respectively. The spleen DNA was digested to completion with EcoRI, which cleaves the f3 globin gene at codon 122, and the fragments were electrophoresed in agarose. A strip of the gel was transferred to nitrocellulose (12), and the 5.2-kilobase (kb) 5' and 3.6-kb 3' , globin DNA fragments were identified by hybridization to 32P-labeled nick-translated (13) P globin c...

In Finland the haplotype A2, Cw1, B56, DR4, DQ8 is the third most common haplotype in insulin-dependent diabetic (IDDM) patients and has the highest haplotype-specific absolute risk for IDDM. Cw1, B56, DR4, DQ8 haplotypes containing HLA-A alleles other than A2 are infrequent in the population and are not associated with IDDM. Comparison of the A2 and non-A2 haplotypes at the DNA level showed that they were identical at HLA-B, -DR, and -DQ loci. Evidence that class I alleles confer susceptibility to IDDM was obtained from the two HLA-C, -B, -DR and -DQ haplotypes most frequently found in IDDM patients in Finland. A24, A3 and A2 on the Cw3, B62, DR4, DQ8 haplotype, and A28, A2 and A1 on the Cw7, B8, DR3, DQ2 were all found to be associated with IDDM. In Finland these seven haplotypes, including A2, Cw1, B56, DR4, DQ8, account for 33% of diabetic haplotypes and 10.3% of non-diabetic haplotypes (p < 0.00001). The contribution of the class I region to IDDM susceptibility was also apparent in those IDDM patients lacking the disease-predisposing class II alleles. Significantly more non-DR3/non-DR4 IDDM patients (47 of 55) possessed two of the IDDM-associated HLA-A alleles compared to non-DR3/non-DR4 control subjects (40 of 58; p = 0.038). Moreover, IDDM patients confirmed by oligotyping as unable to form a 'diabetes-susceptibility' DQ heterodimer, tended to possess two diabetes-associated HLA-A alleles (12 of 13) compared to control subjects (12 of 20; p = 0.056).