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Mouse erythrocyte-rosette-forming cells (MRFC) were determined in 76 cases of chronic lymphocytic leukaemia (CLL), 19 cases of centroblastic-centrocytic follicular non- Hodgkin's lymphoma (NHL), five cases of hairy cell leukaemia (HCL) and in 62 control patients. The mean percentage of MRFC in B-CLL was 54.8% ± 24.4%, in nodular centro-follicular NHL 2.3%±3%, in hairy cell leukaemia 14.6%± 14.7% and among the controls 3.2%±1.9%. Thus, MRFC appear to be an excellent marker of B-CLL and sometimes the only B cell marker as in 11 cases of SIg negative CLL. There is no correlation between the percentage of MRFC and clinical staging according to Rai classification whereas patients with stage 2 in Binet's classification (isolated splenomegaly) have a significantly lower MRFC percentage (23.4% ± 27.7%; P < 0.05). There is no correlation with prognosis, nor with serum Ig levels. We found no correlation with surface phenotype IgM, IgM-IgD or IgG. Thus, this study does not confirm the hypothesis that MRFC might characterize an immature stage in the B lymphocyte differentiation. However, these results are consistent with another hypothesis which states that lymphocytes in CLL possibly originate from a clonal expansion of a normal B lymphocyte subset, characterized by a low concentration of SIg and a receptor for mouse erythrocytes. [ABSTRACT FROM AUTHOR]

The B-cell panel of the ninth HLDA was applied in a multicentre fashion to cryopreserved cells from 46 patients with acute lymphoblastic leukemia. The reagents were aliquoted and shipped to volunteer participants from the French Groupe d'Etude Immunologique des Leucémies (GEIL). All samples were tested in flow cytometry, and the results collected as of the strength of labeling of the leukemic clone as negative, weak or strong. Among the 64 antibodies tested, the strongest and most frequent staining was observed for CD305 (LAIR), CD229 (Ly9), CD200 (OX-2) and, to a lesser extent, CD361 (EVI2b). Details of the observations, and information about the molecules tested are provided in the manuscript as well as a summary table., (Copyright © 2010 Elsevier B.V. All rights reserved.)

The prognostic significance of CD20 expression in B-cell precursor acute lymphoblastic leukemia (BCP-ALL) has been mostly studied in children and yielded conflicting results. In 143 adults with Philadelphia chromosome-negative BCP-ALL treated in the multicentric GRAALL 2003 trial, CD20 positivity over 20% was observed in 32% of patients. While not influencing complete remission achievement, CD20 expression was associated with a higher cumulative incidence of relapse (CIR) at 42 months (P=0.04), independently of the ALL high-risk subset (P=0.025). Notably, the negative impact of CD20 expression on CIR was only observed in patients with a white blood cell count (WBC) over 30x10(9)/L (P=0.006), while not in those with a lower WBC. In the former subgroup, this impact translated into lower event-free survival (15% vs. 59% at 42 months, P=0.003). CD20 expression thus appears to be associated with a worse outcome, which reinforces the interest of evaluating rituximab combined to chemotherapy in CD20-positive adult BCP-ALL. ClinicalTrials.gov ID, NCT00222027.