Cytotoxicity and hemolysis by an extract of the sponge Pachymatisma johnstonii.

In vitro cytotoxicity on human rhinopharynx KB cells, as well as hemolytic activity on human erythrocytes, was produced by an aqueous extract of the sponge Pachymatisma johnstonii. Optimum temperature and pH were the same for both activities (37 degrees C, pH 5). Moreover, after partial purification, the compounds involved were found in the same chromatographic fraction. These compounds were sensitive to treatment with dithiothreitol, but not with papain or trypsin. Cytotoxicity was destroyed by heat, whereas hemolysis subsisted after the extract was heated to 100 degrees C.

[Antibody-dependent cell-mediated cytotoxicity: a method of predicting the severity of fetomaternal alloimmunization in the Rhesus system? A retrospective study of 32 cases]. / La cytotoxicité anticorps dépendante à médiation cellulaire (A.D.C.C.): un moyen de prévoir la gravité des allo-immunisations foeto-maternelles dans le système Rhésus? Etude rétrospective à partir de 32 cas.

This retrospective study has as its object to find out whether A.D.C.C. has advantages over other techniques that are usually used, namely titres or levels of antibodies. There is no correlation between A.D.C.C. and the levels or titres of antibodies in the 32 cases that were studied. When the level of bilirubin at birth is taken as the criterion of the severity of the illness, A.D.C.C. is the only method that gives a significant correlation with the degree of severity of the condition of the infant (p = 0.01). If the need for treatment is taken as a criterion of the severity of the condition (ultra-violet light or replacement-transfusion), A.D.C.C. shows up as being the better technique. But if one only looks at very anaemic infants the significance becomes much greater (p = 0.001).

[Paroxysmal nocturnal hemoglobinuria. Diagnosis aided by a monoclonal antibody directed against the decay accelerating factor glycoprotein]. / Hémoglobinurie nocturne paroxystique. Diagnostic à l'aide d'un anticorps monoclonal dirigé contre la glycoprotéine decay accelerating factor.

The laboratory diagnosis of paroxysmal nocturnal haemoglobinuria (also called Marchiafava-Micheli disease) is based on the sensitivity of the patient's red cells to complement-induced lysis. In view of the clonal expression of the disease, haemolysis tests are difficult to interpret when the abnormal red cell population is small. The sensitivity of abnormal red cells to haemolysis is due to the absence of proteins attached to the cell membrane by a phosphatidyl-inositol link, which intervene in the regulation of the complement-induced lysis mechanism. Using a monoclonal antibody directed against one of these proteins, the decay accelerating factor (DAF, protein CD 55), makes it possible to diagnose paroxysmal nocturnal haemoglobinuria. DAF expression on patients' blood cells was measured by quantitative agglutination and by indirect flow cytometry. The agglutination test using polybren is a fast detection method, but it may be uninterpretable, notably in cases with positive antiglobulin (Coombs') test. In contrast, DAF expression measured by indirect flow cytometry correlates perfectly with measurement of red cell sensitivity by haemolysis tests. Using the monoclonal antibody by indirect flow cytometry is the method of choice to confirm the diagnosis of paroxysmal nocturnal haemoglobinuria and to measure the proportions of normal and abnormal red cells in case of haematological disorder.

[A further case of albumin auto-agglutination in a blood donor]. / A propos d'un nouveau cas d'auto-agglutination en milieu albumineux chez une donneuse de sang

A blood donor is described whose serum contains an albumin active agglutinin reacting with autologous as well as normal donors red cells. Natrium caprylate present in some commercial albumin preparations is show to be co-responsible for this unusual reaction which cause difficulties or errors in Rh grouping.

[Characterization of murine monoclonal antibodies against fetal erythrocytes]. / Caractérisation d'anticorps monoclonaux murins dirigés contre les érythrocytes foetaux.

Balb/c mice were immunized against papain-treated fetal erythrocytes and splenocytes were fused with Sp2/0-Ag-14 myeloma cells. Several hybrids secreting antibodies directed against antigenic determinants predominantly exposed on fetal and cord cells were selected and cloned twice. Antibodies NaM61-1A2 and NaM61-768 (IgM class) were shown to be specific for an endo-beta-galactosidase-sensitive oligosaccharide chain. The antigen, strongly expressed on fetal and cord cells, was identified as the i blood group antigen. The antibodies represent powerful blood group reagents to be use in conventional agglutination techniques as well as in the gel typing system and in indirect flow cytometry. The antibody NaM46-4A8 (IgG class) is specific for an antigenic structure expressed on fetal cells and accessible only after papain, ficin, bromelin and endo-beta galactosidase treatment. The antigen was not identified.