IMMUNOPHENOTYPE OF ADULT AND CHILDHOOD ACUTE PROMYELOCYTIC LEUKEMIA -CORRELATION WITH MORPHOLOGY, TYPE OF PML GENE BREAKPOINT AND CLINICALOUTCOME - A COOPERATIVE ITALIAN STUDY ON 196 CASES
C. Guglielmi et al., IMMUNOPHENOTYPE OF ADULT AND CHILDHOOD ACUTE PROMYELOCYTIC LEUKEMIA -CORRELATION WITH MORPHOLOGY, TYPE OF PML GENE BREAKPOINT AND CLINICALOUTCOME - A COOPERATIVE ITALIAN STUDY ON 196 CASES, British Journal of Haematology, 102(4), 1998, pp. 1035-1041
Acute promyelocytic leukaemia (APL), characterized by a specific PML-R
AR alpha fusion gene resulting from translocation t(15;17) and by a hi
gh response rate to differentiation therapy with all-trans retinoic ac
id, presents clinical (varying WBC counts, age and treatment outcome),
morphological (hypergranular M3 and hypogranular M3V) and molecular (
three isoforms of PML breakpoint) heterogeneity. We correlated leukaem
ic immunophenotype with these aspects in 196 molecularly confirmed APL
s (63 children and 133 adults) in Italy. The bcr3 isoform (P=0.05) and
FAB M3V (P=0.05) were more frequent in children. We confirmed in APL
an immunophenotype characterized by frequent expression of CD13, CD33
and CD9 and rare expression of HLA-DR, CD10, CD7 and CD11b. However, w
e recognized CD2 in 28%, CD34 in 23% and CD19 in 11% of cases and demo
nstrated by double labelling that CD34 and CD2 may be co-expressed, CD
2, CD34 and CD19 were significantly intercorrelated, and variably asso
ciated to other features: CD2 and CD34 with PML bcr3 (P<0.001 and P<0.
001, respectively) and with M3V (P<0.001 and P=0.002), whereas only CD
19 was directly correlated with WBC counts and only CD2 positively inf
luenced CR rate (logistic model) and event-free survival (Cox model).
We conclude that immunophenotype plays a role in the determination of
the biological and clinical heterogeneity of childhood and adult APL.