Individual Cell-by-Cell Quantitation of Lymphocyte Surface Membrane Ig in Normal and CLL Lymphocytes and During Ontogeny of Mouse B Lymphocytes by Immunoperoxidase Assay

A new quantitative immunoperoxidase method is presented for determining absolute amounts of peroxidase and. consequently. surface antigen densities of individual cells in B lymphocytes from normal individuals, from subjects with CLI and prolymphocytic leukemia. and during ontogeny of B lymphocytes in the mouse. The following results were observed: (1 ) The density of B antigenic sites was lower on CLI than on normal B lymphocytes. (2) The B antigenic density of leukemic lymphocytes varied less from cell to cell. forming a homogeneous peak on histograms. (3) In a very rare case of CLI. the antigen density was measured at the time of initial diagnosis (22,500 sites or 647 U) and during the development of a blastic crisis (135.000 sites or 2576 U). The cell by cell distribution changed from a homogeneous peak with a low number of antigenic sites per cell to a heterogeneous peak with a high number of antigenic sites per cell. (4) In prolymphocytic leukemia. the density of B antigenic sites was greater than on normal B lymphocytes and much more heterogeneous than on CLI lymphocytes. (5) During ontogeny of B lymphocytes in the mouse. maturation is associated with the appearance of a population of cells of intermediate to high SmIg density. The finding of a decrease in. and altered distribution of. surface markers in CLI is compared with these ontologic findings in the mouse. and the concept that a monoclonal B lymphocyte in CLI may be arrested at a particular stage in its differentiation is discussed.