The prognostic role of CD5 negativity in B-cell chronic lymphocytic leukaemia: a case-control study.

B cells in chronic lymphocytic leukaemia (CLL) usually express the CD5 antigen, which appears to participate in the pathogenesis of autoimmune phenomena. However, 7-20% of B-CLL patients are CD5-. The aim of this study was to assess whether CD5 expression could be used as a discriminating factor for two subgroups of B-CLL. Twenty-nine CD5- B-CLL patients were compared in terms of clinico-biological characteristics and survival with a control group of 29 sex- and age-matched, consecutive CD5+ B-CLL subjects. B-CLL was considered to be CD5- when less than 5% of mononuclear cells expressed CD5 after subtraction of the number of T cells. Splenomegaly, lymph node involvement, and haemolytic anemia were found in CD5+ patients in a significantly higher proportion than in their CD5- counterparts, who presented with an earlier stage of disease. CD5- patients had a median survival of 97.2 (22-130) months, exceeding CD5+ subjects significantly [84.0 (19-120) months, p = 0.0025]. CD5- patients seemingly present with milder disease and have a favourable prognosis compared with the vast majority of B-CLL patients who express CD5.