An improved flow cytometric method using FACS Lysing Solution for measurement of ZAP-70 expression in B-cell chronic lymphocytic leukemia.

Background: B-cell expression of ZAP-70, normally expressed in T and NK cells, correlates with poor prognosis in B-CLL. Poor discrimination between ZAP-70 positive and negative cells hampers routine application of flow cytometry. We examined the usefulness of FACS Lysing Solution.