The CLL2 study: preliminary results of flow cytometry immunophenotyping in the first 500 patients

In the period 1984-1987, 500 consecutive, newly diagnosed patients with chronic lymphocytic leukaemia (CLL) have been registered in the still open Danish CLL2-study. As part of patient work-up, the immunological phenotype was established in all patients by immunofluorescence microscopy, and in 458 patients also by flow cytometry, with a panel of polyclonal and monoclonal antibodies. The majority of cases exhibited a CD5-pos, SmIgMD-pos phenotype with faint SmIg-fluorescence, and there is as yet no significant difference in survival between SmIgD-pos and SmIgD-neg cases. Seventy cases were FMC7-pos, a marker associated with a higher B-cell differentiation, and this was significantly correlated with stronger SmIg fluorescence intensity and splenomegaly (Rai stage II). The survival of the FMC7-pos patients was not significantly different from that of the FMC7-neg. Thus, in this preliminary phenotype analysis of the first 500 patients in the CLL2 study, no important prognostic subgroups were detected, although this might be due to the still short observation time (median observation time 532 days).