Immunoglobulin phenotype on B cells correlates with clinical stage of chronic lymphocytic leukemia

The present study examines the relative amounts of surface immunoglobulin (Ig) on lymphocytes obtained from 64 patients with chronic lymphocytic leukemia (CLL) and correlates these findings with the clinical stage of disease. Since the maturing B cell first expresses surface IgM, followed by IgD, and subsequently by IgG, IgA, or IgE, the surface Ig phenotype can be used as a marker of differentiation. Surface Ig was analyzed using the fluorescence-activated cell sorter under carefully controlled conditions. The cells from all patients with CLL were monoclonal with respect to light chain type. Those patients with IgM as the brightest heavy chain class (suggesting relatively immature B cells) had clinically advanced stages of CLL, whereas those with a predominance of IgG (suggesting more mature cells) have a lesser stage of CLL. Thus, the predominant Ig heavy chain class appears to correlate with clinical stage of CLL and provides a clue to the potential aggressiveness of the tumor.