CD5 NEGATIVE B-CELL CHRONIC LYMPHOCYTIC-LEUKEMIA - CLINICAL AND BIOLOGICAL FEATURES OF 42 CASES

Chronic lymphocytic leukemia cell (CLL) usually (95%) express B-phenot ype and the CD5 antigen which is usually present on the surface of nor mal T cells. However, among B CLL, 7 to 20% do not express CD5. The si gnificance of the lack of CD5 expression remains unclear. We reviewed 42 consecutive CD5(-) B CLL seen in three French medical centers from 1985 to 1991 and compared them with 79 CD5(+) B CLL. Immunophenotype s tudies were performed using indirect immunofluorescence under light mi croscopy as well as flow cytometry after 1988. B CLL was considered to be CD5 negative when less than 5% of mononuclear cells expressed CD5 after substraction of the number of T-cells, Cases with CD5(-) B CLL h ad isolated splenomegaly more frequently (p = 2.10(-7)). They frequent ly expressed a higher level of surface immunoglobulin (S-Ig) or the sw itch mu/delta phenotype (p = 4.7 10(-2)). The median survival time was not reached but no significant difference between CD5 negative and po sitive B CLL was observed at the time of our data analysis (p = 0.97). Clinical presentation of CD5(-) B CLL seems to be different from othe r forms of B CLL. Although, no conclusion can be reached in terms of p rognosis, CLL with low expression of CD5 should be regarded as a subty pe of CLL with a different clinical presentation than CD5(+) CLL.