A Comparative Study of the Buoyant Density Distribution of Normal and Malignant Lymphocytes

SUMMARY Density distribution patterns of normal and malignant lymphocytes were compared following centrifugation to equilibrium on linear density gradients. For normal lymphocytes differences in the distribution patterns were observed between: (1) B and T cells, (2) central and peripheral cells, and (3) resting and activated cells. The findings suggested that cell density is determined by cell lineage, the degree of differentiation and the stage of functional activation. Marked differences in the density distribution profiles were also observed among certain types of morphologically distinguishable lymphoproliferations. To some extent density analyses enabled the discrimination between CLL, follicular lymphomas and lymphoblastic lymphomas as well as between O‐ALL and T‐ALL. Density profiles of malignant lymphocytes failed to disclose any features specific for malignancies. But they revealed some similarities with distinct subsets of normal lymphocytes, i.e. between: (1) CLL and bone marrow lymphoid cells, (2) follicular lymphomas and follicular centre cells, and (3) lymphoblastic lymphomas and activated lymphocytes. These findings arc further evidence supporting the hypothesis that the malignant trarisformation of phenotypicalIy different lyrnplioproliferations takes place at different levels of lymphocyte differentiation.