"B" cell origin of malignant cells in a case of American Burkitt's lymphoma. Characterization of cells from a pleural effusion.

Ninety-eight percent of the cells isolated from a malignant pleural effusion in a case of American Burkitt's lymphoma showed membrane fluorescence to antihuman IgM antisera, while only 2% of the cells formed spontaneous rosettes with sheep red blood cells. It is concluded that the Burkitt cells in the malignant effusion are derived from bursal equivalent lymphocytes. Epstein-Barr (E-B) viral titers to both viral capsule antigen and early antigen were not elevated. The significance of these findings is discussed.