O-ACETYL SIALIC-ACID BINDING LECTIN AS A PROBE FOR DETECTION OF SUBTLE CHANGE ON CELL-SURFACE INDUCED DURING ACUTE LYMPHOBLASTIC-LEUKEMIA (ALL) AND ITS CLINICAL-APPLICATION

A novel probe, a 9-O-acetylated sialic acid binding lectin, namely ach atinin(H) (ATN(H)) has been used for the detection of changes on the c ell surface during acute lymphoblastic leukemia (ALL). ATN(H) does not agglutinate normal human erythrocytes, however it is capable of agglu tinating erythrocytes and peripheral blood mononuclear cells (PBMC) of patients suffering from ALL. The differential expression of a key rec eptor, 9-O-acetylated sialo glyco conjugate (9-O-AcSG), on PBMC was ob served using a simple lymphoproliferative assay (LA). The extent of ex pression of 9-O-AcSG was used as an index to distinguish ALL patients of different clinical stages and assess the probability of relapse. Th e amount of ATN(H) needed for maximum stimulation served as a tool to indirectly measure the extent of expression of 9-O-AcSG on PBMC surfac e. The acetylated sialo glycoconjugate was expressed at a very high co ncentration during acute phase of the disease. Subsequently it decreas ed during treatment, persisted during maintenance therapy and reappear ed with relapse. PBMC of normal human donors required 80 times more AT N(H) in comparison to the untreated acute phase ALL patients. No cross reactivity was found in non Hodgkin's lymphoma, chronic myelogenous l eukemia and thalassaemia patients.