Multicolor flow-cytometric, morphologic, and clonogenic analysis of marrow CD10-positive cells in children with leukemia in remission or nonmalignant diseases.

PURPOSE To characterize nonleukemic CD10-positive cells in the marrows of children with leukemia in remission or benign conditions. PATIENTS AND METHODS Seventeen children with acute leukemia in complete remission, 12 with solid tumors, and 17 with benign blood diseases were included in this study. Bone marrow cells were analyzed by multicolor flow-cytometry and polymerase chain reaction (PCR) to detect immunoglobulin gene rearrangement. The CD10-positive cells were purely sorted and examined by light microscopy and single cell hemopoietic progenitor assay. RESULTS In patients with acute leukemia, CD10-positive cells were present in higher proportion after completion of therapy than during chemotherapy. They were also higher in the patients of preschool age than in the older age group with benign blood diseases and solid tumors. These CD10-positive cells were morphologically compatible with immature lymphocytes but some blast-like cells also occurred in this population. Most CD10-positive cells coexpressed CD19 and HLA-DR, although only 10 to 30% coexpressed CD20 and CD34. Although some CD10-positive cells expressed CD34, they did not make any colonies. PCR analysis did not show monoclonal bands in CD10-positive bone marrow cells in any patients in remission. CONCLUSION Marrow CD10-positive cells possess immature B-lymphocyte phenotype and are present in higher proportion in the marrows of children with acute leukemia in continuous complete remission after completion of therapy and children of preschool age than school-age children with benign diseases or solid tumors without marrow involvement. The clonality of these cells was excluded by PCR, which is a distinct point from CD10-positive ALL blasts.