Incidence and clinicobiologic characteristics of leukemic B-cell chronic lymphoproliferative disorders with more than one B-cell clone.

Leukemic B-chronic lymphoproliferative disorders (B-CLPDs) are generally believed to derive from a monoclonal B cell; biclonality has only occasionally been reported. In this study, we have explored the incidence of B-CLPD cases with 2 or more B-cell clones and established both the phenotypic differences between the coexisting clones and the clinicobiologic features of these patients. In total, 53 B-CLPD cases with 2 or more B-cell clones were studied. Presence of 2 or more B-cell clones was suspected by immunophenotype and confirmed by molecular/genetic techniques in leukemic samples (n = 42) and purified B-cell subpopulations (n = 10). Overall, 4.8% of 477 consecutive B-CLPDs had 2 or more B-cell clones, their incidence being especially higher among hairy cell leukemia (3 of 13), large cell lymphoma (2 of 10), and atypical chronic lymphocytic leukemia (CLL) (4 of 29). In most cases the 2 B-cell subsets displayed either different surface immunoglobulin (sIg) light chain (n = 37 of 53) or different levels of the same sIg (n = 9 of 53), usually associated with other phenotypic differences. Compared with monoclonal cases, B-CLL patients with 2 or more clones had lower white blood cell (WBC) and lymphocyte counts, more frequently displayed splenomegaly, and required early treatment. Among these, the cases in which a CLL clone coexisted with a non-CLL clone were older and more often displayed B symptoms, a monoclonal component, and diffuse infiltration of bone marrow and required early treatment more frequently than cases with monoclonal CLL or 2 CLL clones.

A new cytometric method for the immunophenotypic characterization of bone-derived human osteoclasts.

BACKGROUND: Osteoclast cell function relates to bone resorption. Isolation and characterization of these cells from in vivo sources remain difficult. The aim of this study was to show the feasibility of using flow cytometry to identify and characterize human mature osteoclasts obtained from bone tissues. METHODS: Bone femoral heads obtained as discarded surgical material were used. To check the nature of 121F(+) (a monoclonal antibody specific for human osteoclasts) cells by flow cytometry, we used laser scanning cytometry to analyze simultaneously the immunophenotype and DNA cell content of osteoclast-like cell-enriched bone samples. RESULTS: Results were compared with conventional morphologic and cytochemical studies. The percentage of cells that showed both cytochemical (tartrate-resistant acid phosphatase [TRAP](+)) and immunophenotypic (121F(+)) osteoclast-associated characteristics was very similar (12.5 +/- 6.2 versus 14.7 +/- 11.7; P = 0.46). Laser scanning cytometry showed that 121F(+) cells were bigger (P = 0.04) and they had a higher DNA cell content (P = 0.04) and more nuclei per cell (P = 0.04) than the 121F(-) cells present in the same sample. DISCUSSION: This study relied on the combined use of the 121F(+) antibody and different cytometry-based techniques to characterize the osteoclast populations from human bone.