DETECTION OF SMALL NUMBERS OF MONOCLONAL LYMPHOCYTES-B IN THE BLOOD OF PATIENTS WITH LYMPHOMA

The definition of complete remission and early relapse in patients with lymphoid malignancy is complicated by the difficulty of recognizing the presence of small numbers of malignant lymphocytes in a population of normal lymphocytes. We have used a method based on the cytofluorometric detection of lymphocytes having homogeneous amounts of surface immunoglobulin of one light-chain class to study blood from patients with lymphomas. The test is capable of reliably detecting 10 per cent or less of monoclonal B lymphocytes in normal blood, and it shows a high incidence (30 to 40 per cent) of previously unsuspected monoclonal B lymphocytes in patients who were thought to have no abnormal blood cells according to standard morphologic technics. The ability to estimate the number of such cells may facilitate the planning of therapy and make more meaningful the concept of complete remission. (N Engl J Med 300:1401–1405, 1979) MORE than 80 per cent of lymphoid malignancies involve clonal proliferation of cells of the B-lymphocyte class.1,2 These cells synthesize and bear immunoglobulin on their surface membranes. Several studies have shown that surface immunoglobulin is a clonal marker in the sense that all members of a single clone of B lymphocytes will have immunoglobulin of the same specificity.3 This observation has been used extensively as a test for the presence of B-cell malignancy when large numbers of abnormal cells are present.1,2 Thus, a population of lymphocytes all possessing the same surface immunoglobulin can be reasonably assumed to represent a clone. © 1979, Massachusetts Medical Society. All rights reserved.