Role of immunotyping in chronic lymphocytosis: review of the natural history of the condition in 145 adult patients.

We investigated the clinical value of immunotyping in 145 consecutive adult patients with absolute or relative lymphocytosis: 132 (91%) had B-cell lymphocytosis, 5 (4%) had T-cell lymphocytosis, 2 (1%) had hairy cell leukemia, and 6 (4%) had reactive lymphocytosis. Of the five patients with T-cell lymphocytosis, four were best categorized as having T gamma-chronic lymphoproliferative disease and had an indolent clinical course. Of the 132 patients with B-cell lymphocytosis, 121 (92%) had B-cell chronic lymphocytic leukemia (B-CLL), and 11 (8%) had small cleaved ("lymphosarcoma") cell leukemia. Patients with small cleaved cell leukemia had a worse clinical outcome than did those with B-CLL. We further analyzed the surface immunoglobulin (sIg) and CD20 (B-1) antigen expression patterns in B-CLL to determine whether any correlation existed with clinical outcome. A subset of patients with B-CLL in whom sIg was expressed in less than 20% of their lymphocytes had the best clinical outcome. HLA-DR (Ia-like) antigen typing helped identify B-CLL cases with minimal or no sIg expression. CD20 (B-1) antigen was weak or undetectable in most cases of B-CLL. Patients with B-CLL who had CD20 (B-1) in more than 20% of their lymphocytes did not have a different prognosis. Our data provide the incidence and natural history of the various subsets of CLL in a series of patients at a single institution. The type and extent of immunotyping necessary and practical in the clinical management of patients with CLL are explored.