THE RAPID DIAGNOSIS OF ACUTE PROMYELOCYTIC LEUKEMIA USING PML (5E10) MONOCLONAL-ANTIBODY

Acute promyelocytic leukaemia (APL) is characterized cytogenetically b y t(15;17)(q22:q21) which results in the production of a PML/RAR alpha ! fusion protein. Detection of the translocation or the fusion gene pr oduct is required for objective diagnosis of APL. This can be accompli shed by conventional cytogenetic methods, fluorescence in situ hybridi zation or RT-PCR, Such techniques are time consuming and not universal ly available. The intracellular distribution of the PML protein in pro myelocytes is characteristically altered in APL and this can be detect ed by immunocytochemistry. We have assessed two immunocytochemical met hods, immunofluorescence and alkaline phosphatase-anti-alkaline phosph atase staining (APAAP), with regard to sensitivity, specificity and ra pidity of diagnosis, 85 patients with AML including 15 cases of APL we re studied. Immunofluorescence PML detection was concordant with RT-PC R for t(15;17) in 14/15 (93.3%) cases with no false positives, The neg ative APL case in our series was, a patient with a 5' PML, breakpoint who did not express the reciprocal t(17;15) fusion product. APAAP was concordant in only 6/13 (46%) APL cases with one false positive. In co nclusion, immunofluorescent localization of PML using 5E10 monoclonal antibody is a rapid, sensitive and specific diagnostic tool for APL.