The recognition of N-glycans by the lectin ArtinM mediates cell death of a human myeloid leukemia cell line.

ArtinM, a D-mannose-binding lectin from Artocarpus heterophyllus (jackfruit), interacts with N-glycosylated receptors on the surface of several cells of hematopoietic origin, triggering cell migration, degranulation, and cytokine release. Because malignant transformation is often associated with altered expression of cell surface glycans, we evaluated the interaction of ArtinM with human myelocytic leukemia cells and investigated cellular responses to lectin binding. The intensity of ArtinM binding varied across 3 leukemia cell lines: NB4>K562>U937. The binding, which was directly related to cell growth suppression, was inhibited in the presence of Manα1-3(Manα1-6)Manß1, and was reverted in underglycosylated NB4 cells. ArtinM interaction with NB4 cells induced cell death (IC(50) = 10 µg/mL), as indicated by cell surface exposure of phosphatidylserine and disruption of mitochondrial membrane potential unassociated with caspase activation or DNA fragmentation. Moreover, ArtinM treatment of NB4 cells strongly induced reactive oxygen species generation and autophagy, as indicated by the detection of acidic vesicular organelles in the treated cells. NB4 cell death was attributed to ArtinM recognition of the trimannosyl core of N-glycans containing a ß1,6-GlcNAc branch linked to α1,6-mannose. This modification correlated with higher levels of N-acetylglucosaminyltransferase V transcripts in NB4 cells than in K562 or U937 cells. Our results provide new insights into the potential of N-glycans containing a ß1,6-GlcNAc branch linked to α1,6-mannose as a novel target for anti-leukemia treatment.

Expression of inducible nitric oxide synthase is increased in acute myeloid leukaemia.

Significant activity of inducible nitric oxide synthase (iNOS) has been reported in tumour cells, including chronic lymphoid leukaemic cells. In this study, we analysed the expression of iNOS in 15 untreated patients with acute myeloid leukaemia (AML) and in 7 normal controls. Using flow cytometry and immunocytochemistry, we demonstrated that patients with AML had a high expression of iNOS when compared to controls. There was no correlation between the expression of iNOS and the expression of p53 and K, H, and N-ras mutation and expression, suggesting that the high expression of iNOS is independent of these proteins and could be the result of transcription factors expressed in AML.

Altos valores de adenosín deaminasa plasmática no asociados a fiebre tifoidea / High plasmatic adenosin deaminase activity not associated to typhoid fever

Valores plasmáticos elevados de ADA han sido asociados a fiebre tifoidea y utilizados para su diagnóstico debido a su bajo costo y rápida lectura. Sin embargo, diferentes registros han señalado un aumento de esta actividad en otras enfermedades lo que puede limitar su precisión diagnóstica. Para confirmar si valores elevados de ADA plasmática están asociados específicamente a fiebre tifoidea, se desarrolló un estudio retrospectivo con los registros de este examen desde un laboratorio hospitalario. Diez pacientes fueron identificados (todos ellos hospitalizados). Seis pacientes padecían fiebre tifoidea y los restantes cuatro tenían otras patologías febriles: leucemia mieloide aguda, dermatomiositis y linfoma no Hodgkin (n=2). Los valores de ADA plasmática fueron similares en ambos grupos pero los pacientes sin fiebre tifoidea se caracterizaron por tener simultáneamente una mayor edad (>35 años) y velocidad de eritrosedimentación (>50 mm/h) (p = 0,004, test de Fisher bilateral). Estos resultados indican que valores plasmáticos elevados de ADA tienen una baja especificidad para el diagnóstico de fiebre tifoidea en pacientes hospitalizados y pueden estar asociados a enfermedades malignas o autoinmunes

Monoclonal antibody anti-MPO is useful in recognizing minimally differentiated acute myeloid leukaemia.

The enzyme myeloperoxidase (MPO) is the most specific marker of myeloid lineage. The recognition of acute myeloid leukaemia (AML) with minimally differentiation (AML-M0) is established with methods that include myeloid markers CD13/CD33 and detection of MPO in blast cells by immunological techniques or electron microscopy cytochemistry (EM). We have analysed the presence of MPO in leukaemic blast cells by conventional cytochemistry and immunological methods using a monoclonal antibody anti-MPO (CLB-MPO1) in 121 cases of acute leukaemia. The aim of the study was to investigate the sensitivity of this McAb to identify AML-M0, as CD13/CD33 can be expressed in some cases of acute lymphoblastic leukaemia (ALL) and EM cytochemistry is not always available in many laboratories. Anti-MPO was positive in all cases of AML (M1-M5) which were positive by Sudan Black B reaction in similar or higher percentage ratio for each case, although in some of them did not label with CD13/CD33 tested by IF and IPc techniques. Based on the anti-MPO positivity, 5 out of 10 cases called undifferentiated leukaemia (AUL) were reclassified as AML-M0, though 4 cases were CD13/CD33 negative. Furthermore, after analysing the anti-MPO expression among 32 cases of ALL, we had to reclassify four of them as acute biphenotypic leukaemia. We conclude that anti-MPO is a very sensitive and reliable tool in AML diagnosis and has an important role in distinguishing minimally differentiated AML and biphenotypic acute leukaemia from AUL and ALL.