Phenotyping of cell surface antigens on peripheral blood lymphocytes is most commonly performed by flow cytometry. Information on both the percentage of lymphocytes positive for a particular antigen and density of these antigens is obtained. L. Two kinds of large granular lymphocytosis occur. In most cases, the proliferating lymphocytes are positive for CD3 and, hence, are considered T-cells. In a minority of cases, CD3 is absent and the proliferating cells are NK cells.
Some cases behave aggressively while many are clinically benign.
Circulating follicular lymphoma is probable if CD10 is positive and CD5 is negative. Phenotyping should be correlated to morphology, lymphadenopathy reassessed, and staging considered. CD11c and CD25 are less specific, but are often very bright in hairy cell leukemia. B-cell CLL should be suspected if CD5 is positive and CD10 is negative. This can usually be confirmed by a phenotypic pattern that includes stronger CD19 than CD20 intensity, weak expression of surface immunoglobulin, and CD23 positivity.