Clinical and cell surface marker characterization of the early phase of chronic lymphocytic leukemia.

The immunologic surface markers on lymphocytes and clinical characteristics of 35 patients with established (stages 0-4) CLL with absolute lymphocyte counts greater than 15,000/cu mm were compared to those of a group of 25 patients with CLL in an early or preleukemic phase (counts of less than 15,000/cu mm). We found a monoclonal B cell proliferation in most cases in the latter group, in spite of the paucity of clinical and laboratory findings. Furthermore, early CLL can readily be distinguished from benign lymphocytosis by surface marker criteria. In untreated CLL, surface marker characteristics are stable with time and predominantly reflect expansion of clones expressing only B cell markers; however, small increase of blood T cells are often seen. Surface markers are a simple and clinically useful tool for definding and characterizing the preleukemic phase of CLL and its ultimate progression to established CLL.