Immunophenotypes in "classical" B-cell chronic lymphocytic leukemia. Correlation with normal cellular counterpart and clinical findings. This study evaluates the expression of a series of membrane antigens, normally expressed by B-lymphocytes of the lymphocytic mantle and marginal zone, in 90 selected cases of "classical" (mouse red blood cell-receptor+, CD20+, CD5+, surface immunoglobulin +/-) B-chronic lymphocytic leukemia (B-CLL) with the aim of contributing toward identifying the normal counterpart of B-CLL and any correlations between surface antigen pattern and certain clinical characteristics. Clustered (CD23, 25, 39, 40, 27, 1c, w75) and unclustered (NuB1, 7F7, KiB3) monoclonal antibodies (MoAb) were tested. Almost all cases showed high reactivity to CD23, 27, w75, 39, 40, and NuB1: expression of CD1c was very low and that of 7F7, KiB3, and CD25 was variable. The reactivity of 7F7 and KiB3 was strictly correlated, and they correlated individually with CD25. Results show that the most frequent B-CLL phenotype (CD19+, 5+, 23+, 27+, 39+, NuB1+, KiB3 +/-, 7F7 +/-, and CD25 +/-) corresponds to one or more cellular subsets in the mantle zone. No correlation was found between MoAb expression, surface immunoglobulin (SIg) class or type, clinical stage, disease activity, or age at diagnosis. The only difference (statistically borderline) was the expression of 7F7 and KiB3 (in young versus old patients). This suggests that modulations in the expression of surface antigens do not affect the clinical behavior of the disease. 