[IgA-mediated auto-immune haemolytic anaemia revealing a hepatitis C virus infection]. / Anémie hémolytique auto-immune à Coombs IgA révélant une infection par le virus de l'hépatite C.

INTRODUCTION: Confirmation of autoimmune hemolytic anaemia usually relies on the detection of erythrocyte membrane-bound autoantibodies using a direct antiglobulin test. In the rare case of IgA autoantibodies-mediated autoimmune hemolytic anemia, the direct antiglobulin test can be negative, because routinely used polyspecific direct antiglobulin test reagents contain only anti-IgG and anticomplement antibodies. EXEGESIS: We report the case of a 41-year-old woman presenting a severe autoimmune hemolytic anaemia caused by the presence of warm autoantibodies of IgA type that revealed a chronic hepatitis C virus infection. CONCLUSION: A negative direct antiglobulin test does not completely rule out the diagnosis of autoimmune hemolytic anaemia especially in the rare case of IgA mediated immune hemolysis. The diagnosis strategy of autoimmune hemolytic anaemia associated with negative direct antiglobulin test and the potential links between autoimmune hemolytic anaemia and HCV are discussed.

Anti-U-like: a common antibody in Black individuals.

BACKGROUND AND OBJECTIVES: Anti-Uz, a scarce antibody, defines a glycophorin B high-incidence antigen, which is protease-sensitive. In a few years, we have encountered 12 antibodies of similar specificity, made by Black individuals of the S- s+ U+ phenotype. MATERIALS AND METHODS: Antibodies were characterized by serological methods, with common and rare MNS types, as well as red cells treated with various proteases. RESULTS: Anti-U-like, mostly an autoantibody, was of IgG class and reacted optimally by indirect antiglobulin test at 20 degrees C. The corresponding antigen was destroyed by several proteases. Tests with papain-treated or Dantu+ cells suggested the existence of several subspecificities. CONCLUSION: Anti-U-like is common in the African population, though its reactions are often misinterpreted. The fact that antibody producers are always Black patients remains unexplained. No relationship with a pathological state could be established.

New murine monoclonal antibodies directed against glycophorins C and D, have anti-Ge2 specificity.

BACKGROUND AND OBJECTIVES: The Gerbich blood group system comprises three high-incidence antigens which have been localized on glycophorins C (GPC) and D (GPD) molecules. Murine monoclonal antibodies (mAbs) directed against Ge4 and Ge3 epitopes have already been obtained. We describe two murine mAbs (ZI51.17 and J6) with Ge2 specificity. MATERIALS AND METHODS: The mAbs were investigated by serological methods and immunoblotting, with common, Ge-negative and enzyme-modified RBCs. RESULTS: Both mAbs behaved like anti-Ge2 in serological tests, but bound to GPC and GPD on immunoblots. ZI51.17 did not recognize the GPCYus or GPCGe variants, whereas J6 revealed a 25-kD component from Ge:-2,-3,4 membranes, which is identical to the GPCGe molecule. CONCLUSION: These two mAbs are directed to slightly different epitopes. The ZI51.17 and J6 epitopes are common to GPC and GPD, thus distinct from the Ge2 antigen defined by human alloantibodies.

Investigation of monoclonal antibodies directed against Fy3, Jra, Lub, Kell or Kell related antigens.

Twenty Mabs of human or murine origin were studied. Serological characterization was achieved by the gel technique with common, rare, and enzyme-modified RBCs. Three clones bound to cell surface proteins on immunoblots: 1 anti-Lub and 2 Mabs raised to a purified Kell glycoprotein. Four anti-K Mabs precipitated the expected 93kD protein and a dimeric form under non-reducing conditions.

Identification of the Fy6 epitope recognized by two monoclonal antibodies in the N-terminal extracellular portion of the Duffy antigen receptor for chemokines.

The epitope Fy6 recognized by two monoclonal antibodies (i3A and BG6), which inhibit binding of chemokines to the Duffy antigen, was characterized by means of peptides synthesized on pins (Epitope Scanning Kit) and deletion mutagenesis. Both antibodies showed very similar specificities. They recognized a linear epitope, the essential portion of which was the heptapeptide Gln-Leu-Asp-Phe-Glu-Asp-Val comprising amino acid residues 21-27, located between two glycosylation sites of the Duffy protein. All the amino acid residues of the epitope, except Glu, were essential for antibody binding, since they could not be replaced by any other amino acid residues or by only one or two. The Glu residue could be replaced by most other amino acid residues, and its replacement by 10 amino acid residues gave a distinct increase in the antibody binding. The results were in full agreement with the finding that the mutant of the Duffy antigen, lacking amino acid residues 23-25 (-Asp-Phe-Glu-), did not bind the i3A antibody, but bound the anti-Fy3 monoclonal antibody similarly to the wild type of the Duffy antigen. The apparent affinity constants of both anti-Fy6 antibodies were determined by surface plasmon resonance, using immunopurified Duffy protein as a ligand.

Production of a new murine monoclonal antibody with Fy6 specificity and characterization of the immunopurified N-glycosylated Duffy-active molecule.

A murine monoclonal antibody (mAb i3A; IgG1, kappa light chain) was obtained using human red blood cells as immunogen. The antibody showed Fy6 specificity since it agglutinated all but Fy(a-b-)-untreated red cells and failed to agglutinate chymotrypsin-treated cells. An erythrocyte membrane protein of 42-46 kD was revealed as the major component recognized by the antibody on immunoblots. The antibody also bound to 92- to 95- and 200-kD proteins, tentatively identified as oligomers of the 42- to 46-kD monomeric form. The affinity-purified Fy6-active protein was converted to a sharp band of 35 kD after N-glycanase treatment. The molecule appeared as a slightly broadly band after neuraminidase treatment but was not further altered by O-glycanase. The i3A mAb bound to 6,000 +/- 1,000 receptor sites on either Fy(a-b+), Fy (a+b+) and Fy(a+b-) red cells with an affinity constant in the range of 3-6 x 10(8) M-1. No binding was observed to other blood cells nor to several cells (B, T, myelomonocytic and erythro-leukemia cell lines). Also, the bulk of i3A-Fy6 immune complexes could be dissociated from the red cell membrane with as low as 0.2% Triton X-100, showing that the Fy6-active glycoprotein is not tightly associated with the membrane skeleton. Our data obtained with a new monoclonal antibody directed to the Fy6 antigen demonstrate that the blood group Duffy-active component is a red cell-specific glycoprotein carrying one or more N-linked oligosaccharides.

t(8;21) prior to acute leukemia.

A t(8;21)(q22;q22) without blood and bone marrow invasion by immature myeloid precursor cells occurred in a patient previously treated for polycythemia vera. The presence of a molecular rearrangement confirmed that the chromosomal abnormality was identical to that observed in acute leukemia with t(8;21). This case shows that the translocation, t(8;21), may occur in myelodysplasia and suggests that it can precede the appearance of overt leukemia.

Serological characterization of murine monoclonal antibodies directed against acquired B red cells.

Balb/c mice were immunized with acquired B red cells. Twelve clones specific for acquired B red cells were obtained from two fusions. A detailed investigation of three clones is reported here. These antibodies appear to be directed to the B-like epitope since they are inhibited by galactosamine and fail to react after acetylation of red cells. E 231 is an example of a series of antibodies closely specific for acquired B red cells which can be useful in elucidating some AB0 typing problems. E 167 and F 47 showed a cross-reactivity with A1 red cells and a synthetic A trisaccharide. No affinity for B antigen could be demonstrated for any of the antibodies.

False negative results in a competitive immunoassay for anti-HIV-antibodies due to the presence of rheumatoid factors.

One serum from a blood donor, which had both HIV-antibodies and rheumatoid factor, gave positive results with EIA anti-HIV screening tests and Western blot, but negative results with the Abbott's ENVACOR assay. Moreover, this serum and 5 out of 6 sera containing only rheumatoid factors were able to interfere with ENV and CORE reactions. Rheumatoid factors bind to the beads used in ENVACOR test and are also able to react with the conjugate. Most of the rheumatoid factors bind to the ENV conjugate, though with a wide range of activity. Obvious binding of rheumatoid factors to the CORE conjugate could not be demonstrated. Binding of rheumatoid factors both to the bead and to the conjugate leads to high optical density values and therefore results in the negative range according to the normal interpretation of the ENVACOR competition procedure.

[True hermaphroditism in a child with a chimeric XX/XY chromosome, a double erythrocyte population and an unusual Lewis (a+ b+) phenotype]. / Hermaphrodisme vrai chez un enfant porteur d'une chimère chromosomique XX/XY, d'une double population erythrocytaire et d'un phénotype Lewis (a+ b+) inhabituel.

A 2 years-old Korean girl is seen because of ambiguous external genitalia. Surgical exploration shows the right gonad to be an ovary and the left one to be an ovotestis, thus demonstrating a true hermaphroditism. Cytogenetic studies of peripheral lymphocytes reveal a mixture of 46,XX and 46,XY cells, with a predominant XX cell line. The patient's red cells are composed of two distinct populations differing in three genetically independent blood group systems. The ratios of the two cell lines in various tissues, especially among the cells secreting Lewis antigens, appear to be very different and suggest several hypothesis to explain the highly unusual red cell Lewis phenotype Le (a+ b+). We conclude to a dispermic chimera, however the adopted status of this child prevents any identification of the maternal or paternal contributions. Because of the physical aspect it was decided to remove the ovotestis, to repair the external genitalia and to bring up this child as a female.

An acute leukaemia augured before clinical signs by blood group antigen abnormalities and low levels of A and H blood group transferase activities in erythrocytes.

A mixed field agglutination pattern with anti-A reagents and very low levels of A and H blood group antigen specific transferase activities were found in the erythrocytes of a 4-year-old girl who presented no clinical signs of haematological disease. Blood and marrow examination displayed some features consistent with a moderate dysmyelopoietic state. 18 months later an acute myeloblastic leukaemia confirmed the suspected haematological malignancy.

[Reaction of anti-I auto-antibodies with erythrocytes from the pig and monkey]. / Réactivité des auto-anticorps anti-I avec les hématies de porc et de singe.

Starting from 5 human sera containing anti-I cold autoagglutinins, it was possible, using adsorption/elution trials with pig's and rhesus monkey's RBC, to separate 8 anti-I antibodies because 3 of the initial sera were heterogeneous. Each of them had 2 anti-I different as regards the reactivity with the animal RBC and the anti-ID or the anti-IF reactivity. On the whole, among 8 separated fractions 1 reacted only on pig's RBC and had the characteristics of an anti-ID; 3 reacted only on rhesus monkey's RBC and were anti-IF; 4 had a cross-reactivity with pig's and monkey's RBC: 2 of them were anti-IF and 2 anti-ID. Anti-ID fixed preferably on pig's RBC and anti-IF on rhesus monkey's RBC but monkey's RBC are not entirely lacking in ID determinants and pig's RBC in IF determinants.

An anti-I cold auto-agglutinin enhanced in the presence of sodium azide.

Difficulty in determining the ABO blood group led to the discovery of an anti-I cold auto-agglutinin in the serum of a blood donor. The peculiarity of this antibody is that its activity is enhanced in the presence of a preservative found in manufactured anti-sera: sodium azide. At 4 degrees C, the auto-antibody agglutinates RBCs even without NaN3 but the drug increases its effect in the cold. At 22 degrees C, the drug is necessary for the adsorption of the antibody on red cells.

[Immunohematological study of 7 cases of acquired B transformation using anti-B and selected acquired anti-B]. / Etude immunohématologique de 7 transformations B acquis à l'aide d'anti-B et d'anti-B acquis sélectionnés.

Seven acquired B samples were studied with selected anti-B sera. Eight sera came from group A subjects, four from group O subjects. The anti-B sera reacting with the acquired B antigen are always a mixture of two kinds of antibodies: a fraction that is only reactive with B antigen, another that is cross-reactive with B and acquired B antigens. In some sera, especially those coming from group O subjects, there is, in addition, a potent antibody of polyagglutination for acquired B red cells. The polyagglutinability associated with acquired B red cells is analysed. According to the results obtained using lectins, four red cell samples are merely acquired B, the three others are acquired B + Tk. The polyagglutinability associated with Tk transformation is non sensitive to acetylation of red cells. The polyagglutinability specific for acquired B is sensitive to acetylation but appears complex in itself. According to the reactivity of selected sera for acquired B samples and the studies of inhibition with simple sugars, there are at least two antigens involved. One of them is present in all of the acquired B samples and it is likely to have arisen from the action of a deacetylase on a structure including N-acetylgalactosamine.

[Acquired B antigen: a new case]. / Antigène B acquis: une nouvelle observation.

A 86 year old woman, in good health but "Escherichia coli" urinary infection, was found to have an abnormality in blood group determination. 3 years ago, blood group of this patient was group A and now, precise determination shows the existence of an acquired B antigen. Disappearance of this acquired B Ag was obtained in 3 months after the urinary infection's treatment. The most cases of acquired B Ag result from neoplasic diseases or infection with enterobacteriacea. Physiopathology of acquired B Ag is secondary to the action of a deacetylase enzyme produced by enterobacteriacea, on group A1 erythrocytes.