A colorimetric assay to evaluate the chemotherapeutic response of children with acute lymphoblastic leukaemia (ALL) employing Achatinin_H: a 9-O-acetyl sialic acid binding lectin

Abstract

Employing a 9-O-acetyl sialic acid binding lectin, Achatinin_H (ATN_H), we have reported a non-invasive, blood based lymphoproliferation assay which measures the maximal lymphoproliferative dose (MLD) of ATN_H to assess the status of 9-O-acetylated sialoglycoconjugates (9-OAcSGs) in patients with Acute lymphoblastic leukemia (ALL) (Mandal C, Sinha D, Sharma V, Bhattacharya DK. O-acetyl sialic acid binding lectin, as a probe for detection of subtle changes on the cell surface induced during acute lymphoblastic leukemia [ALL] and its clinical application. Ind J Biochem Biophys 1997;34:82; Sinha D, Mandal C, Bhattacharya DK. Development of a simple blood based lymphoproliferation assay to assess the clinical status of patients with acute lymphoblastic leukemia. Leuk Res 1999;13:309-312; Sinha D, Mandal C, Bhattacharya DK. A novel method for prognostic evaluation of childhood acute lymphoblastic leukemia. Leukemia 1999;13[in press]). Although the expression of 9-OAcSGs clearly serves as an index of treatment outcome, the assay has limitations in that it requires radioisotopes, i.e. [³H]-TdR. Therefore a colorimetric assay was developed as an alternative approach. The pre-treatment MLD, as measured by the colorimetric assay, was 0.15±0.02 μg which progressively increased during consolidation therapy (1.40±0.39 μg), maintenance therapy (4.20±1.60 μg) and in followed-up cases (5.20±0.43 μg) but sharply declined following relapse (0.25±0.02 μg). The colorimetric assay also showed a good correlation with radiometric assay (r=+0.93) and their mean coefficient of inter-assay precision were also comparable (15.53% versus 14.86%). We therefore propose that the colorimetric assay is a safe, non-radiometric, user-friendly alternative for assessing individual chemotherapeutic responses in childhood ALL.