CD10 and CD19 fluorescence intensity of B-cell precursors in normal and leukemic bone marrow. Clinical characterization of CD10(+strong) and CD10(+weak) common acute lymphoblastic leukemia

In order to assess the age-related changes in CD10 and CD19 fluorescence in tensity (FT) the present study analyzed by flow cytometry 56 sternal biopsi es from 'normal' infants, children and adults undergoing cardiac surgery. T he CD10(+weak) subset was predominant in all age groups, representing appro ximately 50% of the bone marrow (BM) lymphoid cells in children younger tha n 4 years. Both CD10(+) subsets significantly decreased with age but their ratio did not differ significantly. Moreover, the intensity of CD10 and CD1 9 fluorescence in the strong and weak subsets did not vary with age. The CD 19 intensity was significantly higher in CD10(+weak) than in CD10(+strong) cells. In addition, we classified as CD10(+weak) or CD10(+strong) the leuke mic cells from BM aspirates of 117 patients with common acute lymphoblastic leukemia (cALL) (78 children and 39 adults). A higher frequency of cases e xpressing the CD19(+) CD10(+strong) phenotype was observed both in children and adults. Children of the CD10(+weak) group tended to be older than thos e of the CD10(+strong) group (median = 7 vs. 4 years, P = 0.07), and presen ted a significantly higher frequency of splenomegaly (93.7 vs. 55%, P = 0.0 4), which was massive in about 60% of these cases. Among adults, a signific antly higher frequency of cases expressing the CD10(+weak) phenotype was ob served in females. No other clinical or biological difference was detected between the two groups either for children or adults. Concerning the treatm ent outcome, we did not observe significant differences in complete remissi on rate (CRR) or in disease free survival (DFS) among the 32 children and 2 8 adults analyzed. Finally, we compared the CD10 and CD19 intensity in norm al and leukemic BM. Overexpression of either or both antigens in leukemic c ells was observed in 42.4% of the cALL cases. In these cases, using cut off values of 110 afu for the CD10 FI and of 100 afu for the CD19 FI, the dete ction of leukemic cells was possible at levels of 0.2% based on CD10 analys is, of 0.6% based on CD19, and 0.02% when both antigens were overexpressed. In conclusion, we demonstrated that the heterogeneity of CD10 and CD19 flu orescence intensity is of no clinical relevance in cALL, although its study may be helpful for the diagnosis and the detection of minimal residual dis ease. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.