Ultrastructural-characteristics of surface IgM reactive malignant lymphoid cells

Human lymphoblasts from Burkitt-derived cell cultures and from leukemic blood, which displayed surface accumulation of reagents with IgM heavy and ℵ-light chain specificities were studied in thin sections in the electron microscope. Studies using ferritin conjugates were also carried out with other Burkitt cell lines as controls. It was observed that these IgM surface accumulating cells were basically similar to the other Burkitt-derived cell lines and other lymphoblasts; however they did possess some distinctions; they possessed vesicles in the Golgi area filled with granular material, prominent polyribosomes, and increased numbers of multivesicular bodies. Ferritin conjugated antibody accumulated in a similar fashion to fluorescein conjugated reagents and was absent from the surface of the control cells. The possible implications of these findings was discussed.