Monoclonal antibodies specific for the M- and N-forms of human glycophorin A

A 42K outer-membrane protein is a component of the yeast mitochondrial protein import site

An engineered precursor protein that sticks in the import site of isolated yeast mitochondria can be specifically photo-crosslinked to a mitochondrial outer-membrane protein of relative molecular mass 42,000 (42K). This protein (termed import-site protein 42 or ISP 42) is exposed on the mitochondrial surface; antibodies against it block protein import into mitochondria. ISP 42 is the first identified component of the putative transmembrane machinery that imports proteins into mitochondria.

Unmyristylated Moloney murine leukemia virus Pr65gag is excluded from virus assembly and maturation events

The gag precursor polyprotein of Moloney murine leukemia virus (MuLV) is normally modified by myristylation of the N-terminal glycine. Previous work showed that the Pr65gag lacking the myristylation site does not associate with cellular membranes or assemble into virus particles. We now report that it also is not cleaved to the mature gag cleavage products within the cell and that it sediments as a free 65-kilodalton monomer in detergent-free cell extracts containing 0.3 M NaCl. Even when the cells containing the mutant are productively infected with wild-type MuLV, the mutant Pr65gag is not processed into cleavage products and is not incorporated into the virions produced by these cells. Thus, the mutant gag molecules seem unable to participate in the normal processes of self-assembly and maturation. We propose that myristate-mediated membrane association is an essential first step in MuLV assembly. This association may also play a role in budding of MuLV.

Alteration of the genes for glycophorin A and B in glycophorin-A-deficient individuals

Glycophorins A and B are homologous glycoproteins of the red cell membrane which carry the blood-group MN and Ss antigens, respectively, and are encoded by two distinct genes closely linked on chromosome 4, which are probably derived from each other by duplication during evolution. The lack of glycophorin A is associated with the rare phenotype En(a-), indicating individuals who are defective for MN antigens, as well as for the Ena antigens, also located on this glycoprotein. The En(a-) condition is heterogenous and includes two categories of variants exemplified by the Finnish and the English types referred to as En(Fin) and En(UK), respectively. By Southern blot and preliminary genomic clone analyzes we have compared the status of the genes for glycophorins A and B, as well as that of the gene encoding glycophorin C, another unrelated red cell membrane glycoprotein, in the En(a-) variants and in the En(a+) control donors. Our data indicate that the En(Fin) variant is homozygous for a complete deletion of the glycophorin A gene without any detectable abnormality of the genes encoding glycophorins B or C. In the genome of the En(UK) variant, with the presumed genotype Mk/En(UK), and where the Mk condition abolishes the expression of MN and Ss antigens, we have identified several abnormalities of the glycophorin A and B genes, but the glycophorin C gene was unaffected. Our results strongly support the view that in Mk chromosome the glycophorin A and B genes are largely deleted, whereas the En(UK) chromosome probably contains a gene fusion product encoding a hybrid glycoprotein AM-B, composed of the N-terminal portion of a blood group M-type glycophorin A and of the C-terminal portion of glycophorin B. The determination of the 5' and 3' limits of the hybrid gene and elucidation of the mechanism involved will require sequencing of the rearranged DNA of the variant and a full knowledge of the organization of the glycophorin A and B genes.

Signal transduction by glycophorin A: role of extracellular and cytoplasmic domains in a modulatable process

Binding of ligands to the extracellular region of the erythrocyte transmembrane protein glycophorin A induces a decrease in membrane deformability. Since the property of membrane deformability is regulated by the skeletal proteins on the cytoplasmic side of the membrane, this suggests that ligand binding may initiate a transmembrane signal. To further study this process, we examined which domains of the extracellular region of glycophorin are involved in signal transduction and whether the cytoplasmic domain of the molecule is necessary for transmitting the signal. Using the ektacytometer, we compared the effect on deformability of four monoclonal antibodies that detect different epitopes on glycophorin A. We found that 9A3 (which recognized the amino terminus of glycophorin) caused a 5.8-fold increase in rigidity, R-10 and 10F7 (which recognized epitopes in the mid-region of the extracellular domain) caused a 10.8-fold increase in rigidity and B14 (which binds to glycophorin close to the membrane) caused a 18-fold increase in rigidity. Further, a direct relationship was observed between the degree of antibody-induced rigidity and the amount of glycophorin A that became associated with the skeletal proteins in a Triton shell assay. In Miltenberger V erythrocytes, which contain a hybrid sialoglycoprotein with no cytoplasmic domain, antibody binding did not induce an increase in rigidity. These results imply that glycophorin A is capable of a modulatable form of transmembrane signaling that is determined by the extracellular domain to which the ligand binds, and the cytoplasmic domain of glycophorin A is crucial for this process.

Hybrid sialoglycoprotein content of St(a+) red cells

St(a+) red cells contain a ficin-resistant hybrid sialoglycoprotein (SGP) consisting of the amino terminus of Ss sialoglycoprotein (Ss SGP) and the carboxyl terminus of MN sialoglycoprotein (MN SGP). Ficin-modified St(a+) but not St(a-) red cells were agglutinated by monoclonal antibodies NN5 (anti-N) and 31 (detecting a sialic acid-dependent determinant on the SGPs). SDS-polyacrylamide gel electrophoresis showed three periodic acid-Schiff-staining protein bands in ficin-modified St(a+) but not St(a-) red cell-membranes; these bands bound monoclonal antibodies NN5 and 31 on Western blots. Using Scatchard analysis of 125I-NN5 IgG binding to M+N- red cells, estimates were obtained of 25,000 Ss SGP molecules per red cell per s allele, 33,000 Ss SGP molecules per red cell per S allele, and 75,000 hybrid SGP molecules per red cell per hybrid allele. These results are consistent with the expression of the hybrid SGP gene at a level intermediate between the MN SGP gene and the Ss SGP gene. Monoclonal antibodies NN5 and 31 may be useful in screening ficin-treated red cells for hybrid SGP variants.

Acinetobacter cyclohexanone monooxygenase: gene cloning and sequence determination

The gene coding for cyclohexanone monooxygenase from Acinetobacter sp. strain NCIB 9871 was isolated by immunological screening methods. We located and determined the nucleotide sequence of the gene. The structural gene is 1,626 nucleotides long and codes for a polypeptide of 542 amino acids; 389 nucleotides 5' and 108 nucleotides 3' of the coding region are also reported. The complete amino acid sequence of the enzyme was derived by translation of the nucleotide sequence. From a comparison of the amino acid sequence with consensus sequences of nucleotide-binding folds, we identified a potential flavin-binding site at the NH2 terminus of the enzyme (residues 6 to 18) and a potential nicotinamide-binding site extending from residue 176 to residue 208 of the protein. An overproduction system for the gene to facilitate genetic manipulations was also constructed by using the tac promoter vector pKK223-3 in Escherichia coli.

Stimulation of human hematopoietic colony formation by recombinant gibbon multi-colony-stimulating factor or interleukin 3

Recently, the gene for a novel mammalian hematopoietic growth factor homologous to murine interleukin 3 was isolated from a gibbon T cell line and expressed in monkey COS cells. The factor, termed multi-colony stimulating factor (multi-CSF) or interleukin 3, is stimulatory to human target cells. We investigated the range of enriched human bone marrow and fetal liver hematopoietic progenitors responsive to multi-CSF; compared the colony types observed with those obtained in the presence of recombinant granulocyte-macrophage CSF (GM-CSF); and analyzed the effects on colony formation of combining multi-CSF with GM-CSF or granulocyte-CSF (G-CSF). The results show that multi-CSF acts as a multipoietin. Alone it stimulates the formation of colonies derived from granulocyte, macrophage, eosinophil, and megakaryocyte progenitors. In combination with erythropoietin it supports the development of both erythroid and mixed colonies. Furthermore, the data show that multi-CSF is a more potent stimulus of erythroid progenitors than GM-CSF. In combination with G-CSF multi-CSF substantially increases granulocyte colony number over the number obtained with each factor alone. We conclude that multi-CSF may prove to have important therapeutic potential in vivo as a stimulus for hematopoiesis.

Glycophorin is the reovirus receptor on human erythrocytes

Purified glycophorin (predominantly type A) from human erythrocytes was found to effectively inhibit reovirus hemagglutination (HA) in contrast to other glycoproteins such as fetuin or ovalbumin. Glycophorin was also a potent inhibitor of reovirus and protein sigma 1 binding to mouse L fibroblasts. Glycophorin pretreated with neuraminidase lost these inhibitory properties. Using a solid phase binding assay, it was demonstrated that reovirus as well as protein sigma 1 could specifically bind to glycophorin immobilized on polystyrene plates. This binding was inhibited by wheat germ agglutinin (WGA) but not by other lectins such as peanut agglutinin (PA), Maclura pomifera agglutinin (MPA), Bauhinia purpurea agglutinin (BPA), or concanavalin A (Con A). Binding of reovirus to glycophorin was also partially inhibited by a monoclonal antibody (10F7) (W. L. Bigbee, R. G. Langlois, M. Vanderlaan, and R. H. Jensen, 1984, J. Immunol. 133, 3149-3155), which recognizes a determinant common to the M and N forms of glycophorin, but not by N-specific monoclonal antibodies NN4 and NN5 or an M-specific monoclonal antibody, 6A7. Taken together, these results clearly indicate that the M, N blood group antigen, glycophorin, is the erythrocyte receptor for reovirus.

A monoclonal anti-glycophorin A antibody recognizing the blood group M determinant: studies on the subspecificity

A mouse monoclonal antibody (425/2B, IgM) was obtained which shows specificity for blood group M determinant of glycophorin A. The antibody is pH-dependent. At pH 6-7 it reacted strongly with blood group M antigen, but also cross-reacted distinctly with N antigen. At pH 8.3 the antibody showed moderately decreased reactivity with M antigen, but no interaction with N antigen was detectable by hemagglutination, immunoblotting, or microplate ELISA. The direct binding studies and inhibition of 425/B antibody by untreated or modified blood group M and N glycoproteins or tryptic glycopeptides showed that the binding to the antigens was not affected by acetylation of their amino groups, or removal of amino-terminal amino acid residue. Desialylation of the antigens decreased their reactivity with the antibody and this effect was distinctly stronger at pH 7 than 8.3. The antibody reacted strongly at pH 7 and 8.3 with glycophorin B of Henshaw phenotype, whereas its reactivity with normal glycophorin B was weak or undetectable at these pH values, respectively. The results obtained indicated that anti-M specificity of 425/2B antibody is related to the 5th amino acid residue of glycophorin A (anti-Mgly specificity) and that pH shift from 7 to 8.3 changes the fine specificity of the antibody. At pH 8.3 the reactivity of the antibody is more dependent on glycine residue (higher anti-M specificity) and less dependent on sialic acid residues in the antigen.

Monoclonal antibodies to human protamines

Nine monoclonal antibodies to human protamine, hup1a, 1b, 1c, 1d, 1e, 2a, 2b, A, and B, have been isolated and partially characterized. Enzyme-linked immunoabsorption assay analyses with HPLC-separated human protamine 1 and protamine 2+3 mixture identified five of these antibodies as specific for human protamine 1, two antibodies specific for protamine 2+3 mixture and two monoclonal antibodies reactive with all three human protamines. These findings were confirmed by immunoblotting. None of the antibodies reacted with poly-arginine or somatic histone proteins. Additional analyses with bull, boar, and ram protamines indicated that all of the monoclonal antibodies except hupA are specific for human protamine. HupA reacted with protamines from all of the species tested. These studies suggest that each of the antibodies recognizes one of at least four distinct epitopes on protamine.

Severe hemolytic disease of the newborn due to anti-Vw and detection of glycophorin A antigens on the Miltenberger I sialoglycoprotein by Western blotting

Anti-Vw detecting an antigen on Miltenberger I (Mi I) variant glycophorin A (GPA) has rarely been reported as a cause of hemolytic disease of the newborn (HDN). We report an infant with severe HDN due to anti-Vw. Examination of the Vw+ erythrocytes of the father and paternal grandmother by sodium dodecylsulphate polyacrylamide gel electrophoresis showed an extra trypsin-sensitive, periodic-acid-Schiff staining band, consistent with Mi I variant GPA. Staining of Western blots by monoclonal antibodies showed that normal paternal GPA expressed blood group M, while Mi I variant GPA expressed blood group N. Mi I variant GPA expressed the trypsin-sensitive antigenic determinant detected by MoAb 10F7, indicating that the alterations known to occur in the trypsin-sensitive fragment of Mi I variant GPA do not affect expression of the antigen detected by 10F7.

Multipotent human hematopoietic cell line K562: lineage-specific constitutive and inducible antigens

K562 cells have been reported to display a variety of non-erythroid properties. Using 28 lineage-specific monoclonal antibodies, we analysed which antigens are present spontaneously and which are inducible by a variety of agents. The data suggest that (1) antigens of a given lineage are preferentially responsive to certain inducers, e.g. megakaryocytic antigens to phorbol ester, and (2) a given inducer may influence antigens of different lineages in opposite directions, e.g. phorbol dibutyrate, not only induces megakaryocytic antigens, but also decreases granulocyte and erythroid antigens. We conclude that the K562 cell, despite its malignant origin, retains some capacity for expression of alternative programs of differentiation, a characteristic of the normal multipotent hematopoietic stem cell.

Interleukin 1 induces cultured human endothelial cell production of granulocyte-macrophage colony-stimulating factor

Monokine-stimulated endothelial cells are known to produce both burst- and colony-stimulating activities, but neither the nature of the monokine nor the hematopoietic growth factor(s) produced is known. We show by mRNA analysis that an immortalized line of human endothelial cells constitutively produce granulocyte-macrophage colony-stimulating factor. Furthermore, interleukin 1 and tumor necrosis factor induce early passage human umbilical endothelial cells to produce the same growth factor.

Measurements of the frequency of human erythrocytes with gene expression loss phenotypes at the glycophorin A locus

An assay method is described for determining the frequency of human erythrocytes having a gene expression loss phenotype at the glycophorin A locus presumably due to in vivo somatic mutational events in erythroid precursor cells. Monoclonal antibodies specific for the M and N glycophorin A alleles are used to identify variant cells that lack the expression of one allele in blood samples from MN heterozygotes. Flow cytometry and sorting are used to enumerate and purify variant cells. Using three different antibody combinations which are sensitive to the loss of either the M or the N allele, we find that variant cells occur at a frequency of 1 X 10(-5) in normal donors. We also detect variant cells with an apparent homozygous phenotype suggesting that events leading to homozygosity may occur at similar frequencies to gene loss events. Significant increases in variant cell frequency are observed in cancer patients after exposure to mutagenic chemotherapy drugs.

Improved high-affinity monoclonal antibody to iododeoxyuridine

Three monoclonal antibodies (Mabs), IU-1, IU-4, and B-44 were evaluated in enzyme immunoassays (ELISA) and by flow cytometry for their abilities to recognize bromodeoxyuridine (BrdUrd)- and iododeoxyuridine (IdUrd)-substituted DNA's, nucleotides, and nucleosides. IU-4 is a new Mab, derived from mice immunized with 5-iodo-2'-deoxyuridine-5'-monophosphate (IdUMP) conjugated (IdUMP) conjugated through the phosphate group to albumin. This immunogen was selected to resemble IdUMP in DNA. In competition ELISA assays, IU-4 prefers IdUrd to BrdUrd and prefers halogenated nucleotides over the corresponding nucleosides. In both ELISA and flow analysis, IU-4 recognizes IdUrd in DNA at substitution frequencies at least as low as one IdUrd one per 1,000 normal bases. The high affinity of IU-4 for IdUrd-DNA contrasts with IU-1 and B-44, which show a strong binding dependency on the frequency of base substitution and require DNA that is essentially fully substituted with BrdUrd for binding in both flow and ELISA assays. The high affinity of IU-4 for IdUrd in DNA and its independence of IdUrd residue spacing make it a superior reagent for the quantitative labeling of halogenated thymidine analogues in whole cells.

Reactions of murine monoclonal antibodies to blood group MN antigens

BALB/c mice were immunized by intraperitoneal injections with human blood group substances; 4 mice with M and 4 with N. Immune spleen cells were fused with murine myeloma cells X63-Ag-8.653. Two clones secreting monoclonal anti-M and seven secreting monoclonal anti-N were identified. All antibodies were of IgG1 subclass and had kappa light chains. Three clones have been maintained that produced antibodies useful for typing purposes: anti-M, A09 originating from a mouse injected with M, anti-N, AH7 originating from a mouse injected with N, and anti-N BO10 originated from a mouse injected with M substance. In typing 370 erythrocyte samples, monoclonal reagents gave identical results with commercial anti-M or anti-N typing sera of rabbit origin. Significantly, anti-N reagent AH7 obtained by immunization with N substance showed serological differences from anti-N reagent BO10 obtained by immunization with M substance in that AH7 had apparently higher avidity to N specificity on glycophorin A of N erythrocytes than BO10, whereas BO10 showed higher avidity for 'N' specificity on glycophorin B of M and N erythrocytes than AH7. These two reagents showed also somewhat different patterns of reaction with enzymatically digested erythrocytes. This apparent serologic difference between N and 'N' specificities is at variance with current immunochemical data.

Expression of proliferating cell nuclear antigen (PCNA)/cyclin during the cell cycle

The expression of proliferating cell nuclear antigen (PCNA), also called cyclin, was quantified in the cell lines SP2/0 and MOLT-4 and in mouse splenocytes induced to proliferate in vitro with mitogens. Autoantibody from a patient with systemic lupus erythematosus was used to label PCNA in cell suspensions after the cells had been fixed and permeabilized. In the same cells DNA was stained by propidium iodide. The cells were then analysed by flow cytometry for PCNA and DNA content. The PCNA profiles in proliferating spleen cells and the cell lines were similar. Most G0-G1 cells did not express significant amount of PCNA. A dramatic increase in PCNA immunofluorescence was observed in late G1 cells, and further increases were observed in S-phase cells. G2-M cells showed a reduced level of PCNA immunofluorescence relative to S-phase cells but were still elevated relative to G0-G1 cells. Proliferating cells arrested at the G1-S boundary by exposure to cytosine arabinoside showed an increased PCNA immunofluorescence as compared to unstimulated cells.

Possible role of the carbohydrate residues on the structure of the N-terminus of glycophorin AM

Natural-abundance 13C nuclear magnetic resonance (13C-n.m.r.) was used to study the effect of monoglycosylation on the structure and dynamics of a pentapeptide related to the N-terminus of glycophorin AM. The results of this study indicate that a single point of glycosylation, on the pentapeptide, can significantly affect its structure. Moreover, glycosylation of this pentapeptide also affects its dynamic motion in solution. This study further defines the role that the carbohydrate residue plays in determining the structure about the N-terminus of glycophorin AM.

Monoclonal antibody for DNA measurement in biological fluids

Two highly sensitive immunoassays for measuring soluble DNA are described. These methods employ a purified mouse monoclonal anti-DNA antibody in enzyme-linked immunoassays. One assay is an antigen capture method utilizing immobilized antibody. Bound DNA is subsequently detected with biotinylated monoclonal anti-DNA antibody, avidin-coupled horseradish peroxidase and a chromogenic substrate. The limit of detection of the assay was 2 ng/ml of DNA. A competition assay relying on immobilized heat-denatured DNA was also designed. In this assay the solution to be analyzed is mixed in equal proportions with monoclonal anti-DNA antibody and the mixture is incubated in the DNA-containing microtiter plates. The inhibition of antibody binding as detected with peroxidase-conjugated anti-mouse IgG was proportional to the concentration of DNA in the sample. The competition assay was tested for its ability to detect DNA in human plasma. The detection limit of DNA in plasma was approximately 150 ng/ml. The assays were compared in their ability to detect various size fragments of DNA. The competition assay was capable of detecting DNA fragments as small as 30 base pairs. In contrast, the capture assay failed to detect low molecular weight fragments up to 150 base pairs although its sensitivity for undigested DNA was comparable to the competition assay. The assay may be of use in the rapid quantitation of low levels of DNA, especially low molecular weight DNA and may also be useful in measuring DNA in human plasma.

Tandem purification of IgM monoclonal antibodies from mouse ascites fluids by anion-exchange and gel fast protein liquid chromatography

A tandem chromatographic procedure was used to isolate rapidly mouse IgM monoclonal antibodies. Mouse ascites fluids containing IgM monoclonal antibodies were first chromatographed on an anion-exchange Mono Q column connected to a fast protein liquid chromatography system. The IgM-rich fractions from the Mono Q column were then injected on a gel filtration Superose 6 column equilibrated with a low-ionic strength buffer and eluted with a high-ionic strength buffer. Assessment of the purity of isolated IgM monoclonal antibodies was performed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis together with a Coomassie Brillant Blue R 250 staining technique. Assessment of the immunoreactivity of isolated IgM monoclonal antibodies was performed by a enzyme linked immunosorbent assay using a solid phase adsorbed antigen against which IgM monoclonal antibodies were directed. The chromatographic procedure described provides a new method for the rapid purification of mouse IgM monoclonal antibodies to a high degree of purity and in a immunoreactive state.

Characterization of monoclonal antibodies to bromodeoxyuridine

The characteristics of three mouse monoclonal antibodies to halogenated uridine derivatives are presented. Two, IU-1 and IU-2, are produced by hybridomas derived in our laboratory, and the third is the B-44 hybridoma described by Gratzner (7) and obtained commercially from Becton-Dickinson Monoclonal Center. Hybridomas IU-1 and IU-2 were derived from the fusion of spleen cells from a Biozzi High Responder mouse immunized with iododeoxyuridine (IdUrd) conjugated to bovine serum albumin and SP2/0 mouse myeloma cells. This paper presents methods and results for enzyme-linked immunosorbent assays (ELISA) against whole cells labeled with bromodeoxyuridine (BrdUrd), ELISA against BrdUrd-labeled DNA, and a competition ELISA for free BrdUrd. All three antibodies show similar binding affinities and specificities. The IU antibodies react with BrdUrd and IdUrd when the nucleosides are either free in solution or incorporated into single-stranded DNA (ss-DNA). The antibodies do not recognize either halogenated base in double-stranded DNA (ds-DNA), nor do they react with uracil or bromocytidine. Weak binding to thymidine, 5-fluorodeoxyuridine, and unsubstituted ss-DNA occurs.

Phospholipid dependence of Wrb antigen expression in human erythrocyte membranes

Phospholipid depletion of human erythrocyte membranes by phospholipase A2 modification markedly decreased binding of two monoclonal antibodies to the Wrb (Wright) blood group determinant on glycophorin A. Binding of seven monoclonal antibodies to other glycophorin A determinants, including anti-M and anti-N, was unaffected by phospholipid depletion. These results indicate that Wrb antigen expression is phospholipid-dependent in human erythrocyte membranes.

Glycophorin A on normal and leukemia cells detected by monoclonal antibodies, including a new monoclonal antibody reactive with glycophorins A and B

A new hemagglutinating monoclonal antibody, MoAb31, detected glycophorins A and B in Western blots. Results with enzyme-modified erythrocytes indicated the MoAb31 determinants were sialic acid dependent, and resided on glycophorin A on the trypsin-resistant, ficin-sensitive segment, and on glycophorin B on the ficin-sensitive segment. Another new monoclonal antibody, MoAb36, detected the Wrb antigen, located on the non-glycosylated segment of glycophorin A near its insertion into the lipid bilayer. Immunofluorescent staining of normal hematopoietic and leukemia cells with these and other monoclonal antibodies to glycophorin A demonstrated glycophorin A on erythroid cells only. Cytofluorograph analysis showed the majority of cells of the erythroleukemia cell lines K562 and HEL expressed glycophorin A, as indicated by reactivity with the monoclonal glycophorin A antibodies R10, R18, 6A7 and 10F7. However, reactivity with monoclonal antibodies to glycosylated determinants (MoAb31 and R1.3) and to the non-glycosylated segment near the membrane insertion (MoAb36, and R7.1) was reduced or absent. Expression of "missing" glycophorin A antigens on K562 and HEL could not be induced using a variety of chemical and biologically active modifiers. We conclude that glycophorin A of erythroleukemia cell lines K562 and HEL differs from glycophorin A at the surface of normal, mature erythrocytes with respect to reactivity with monoclonal glycophorin A antibodies.

Monoclonal antibodies to cyanogen bromide fragments of glycophorin A

Eleven mouse monoclonal antibodies directed against epitopes on CNBr peptides of the major sialoglycoconjugate of the human red blood cell, glycophorin A, have been produced by hybridomas derived from P3-X63-Ag8.653 myeloma cells and spleen cells from BALB/c mice immunized with purified glycophorin. The monoclonal antibodies could be divided into four groups according to their reactivities with CNBr peptides in a direct ELISA assay: one antibody (6B5) that binds solely to the aminoterminal octapeptide (CNBr3); two antibodies (8F10 and 9C3) that bind to CNBrl (residues 9-81); two antibodies (3D2 and 4C6) that are reactive with CNBr2, The C-terminal portion of the molecule (residues 82-131); six antibodies (1B4, 4C3, 4E7, 7B10, 7C11 and 9D6) which are cross-reactive with an epitope on both CNBr1 and CNBR3 glycopeptides. This cross-reactive epitope(s) appears to involve both carbohydrate and protein residues.

One-step purification of mouse monoclonal antibodies from ascites fluid by hydroxylapatite chromatography

A single-step method for purification of mouse monoclonal antibodies directly from ascitic fluids using hydroxylapatite column chromatography is described. The procedure yields highly purified IgG or IgM antibodies. The purified immunoglobulin is essentially free of contaminating mouse albumin, transferrin, and other ascites proteins, as determined by SDS-polyacrylamide gel electrophoresis. Hydroxylapatite chromatography can also separate monoclonal IgG antibodies from contaminating IgG antibodies found in ascites fluid of animals that have been immunosuppressed prior to ascites induction. Furthermore, the evidence presented here suggests that some hybridomas of SP2/0 origin synthesize an extraneous light chain resulting in the secretion of hybrid antibody molecules.

Monoclonal antibodies specific for sickle cell hemoglobin

Two mouse hybridoma cell lines were isolated which produce monoclonal antibodies that bind hemoglobin S. The mice were immunized with peptide-protein conjugates to stimulate a response to the amino terminal peptide of the beta chain of hemoglobin S, where the single amino acid difference between A and S occurs. Immunocharacterization of the antibodies shows that they bind specifically to the immunogen peptide and to hemoglobin S. The specificity for S is high enough that one AS cell in a mixture with a million AA cells is labeled by antibody, and such cells can be analyzed by flow cytometry. Immunoblotting of electrophoretic gels allows definitive identification of hemoglobin S as compared with other hemoglobins with similar electrophoretic mobility.