Relevance of surface markers in chronic lymphocytic leukemia to acute lymphocytic leukemia.

The surface membrane of the B-lymphocyte of chronic lymphocytic leukemia (CLL) has been subject to detailed investigation over the past decade. Surface immunoglobulin of low density, punctate in distribution, without the tendency to polar cap formation, and clonal with respect to light and heavy chains, is characteristic. Other B-cell properties include the presence of the Ia antigen and the receptor for the C3d portion of complement. The CLL surface membrane lacks such T-cell attributes as the ability to form rosettes with sheep erythrocytes and reactivity with anti-T-cell antisera, although T-cells may be increased early in the disorder. CLL is believed to be a proliferation of a B-lymphocyte of the medullary cord of the lymph node, although the exact place of this cell in lymphocyte development remains to be clarified. Surface markers are useful in distinguishing classical B-cell CLL from other proliferations of small lymphocytes (lymphosarcoma cell leukemia of follicle-center B-cells, T-cell CLL, Sézary syndrome, and reactive lymphocytosis).