A colorimetric assay to evaluate the chemotherapeutic response of childrenwith acute lymphoblastic leukemia (ALL) employing Achatinin(H): a 9-O-acetyl sialic acid binding lectin

Employing a 9-O-acetyl sialic acid binding lectin, Achatinin(H) (ATN(H)), w e have reported a non-invasive, blood based lymphoproliferation assay which measures the maximal lymphoproliferative dose (MLD) of ATN(H) to assess th e status of 9-O-acetylated sialoglycoconjugates (9-OAcSGs) in patients with Acute lymphoblastic leukemia (ALL) (Mandal C, Sinha D, Sharma V, Bhattacha rya DK. O-acetyl sialic acid binding lectin, as:a probe for detection of su btle changes on the cell surface induced during acute lymphoblastic leukemi a [ALL] and its clinical application. Ind J Biochem Biophys 1997;34:82; Sin ha D, Mandal C, Bhattacharya DK. Development of a simple blood based lympho proliferation assay to assess the clinical status of patients with acute ly mphoblastic leukemia. Leuk Res 1999;13:309-312; Sinha D, Mandal C, Bhattach arya DK. A novel method for prognostic evaluation of childhood acute lympho blastic leukemia. Leukemia 1999;13[in press]). Although the expression of 9 -OAcSGs clearly serves as an index of treatment outcome, the assay has limi tations in that it requires radioisotopes, i.e. [H-3]-TdR. Therefore a colo rimetric assay was developed as an alternative approach. The pre-treatment MLD, as measured by the colorimetric assay, was 0.15 +/- 0.02 mu g which pr ogressively increased during consolidation therapy (1.40 +/- 0.39 mu g), ma intenance therapy (4.20 +/- 1.60 mu g) and in followed-up cases (5.20 +/- 0 .43 mu g) but sharply declined following relapse (0.25 +/- 0.02 mu g). The colorimetric assay also showed a good correlation with radiometric assay (r = +0.93) and their mean coefficient of inter-assay precision were also com parable (15.53% versus 14.86%. We therefore propose that the colorimetric a ssay is a safe, non-radiometric, user-friendly alternative for assessing in dividual chemotherapeutic responses in childhood ALL. (C) 1999 Elsevier Sci ence Ltd. All rights reserved.