The fine structure of monoclonal Hodgkin cells cultured in diffusion chambers

Pleural effusion cells from two patients with stage IV Hodgkin's disease have been cultured continuously in diffusion chambers in mice and studied by electron microscopy after a culture period exceeding 100 days. Cell identity and monoclonal growth in culture has been documented by marker chromosomes (Hossfeld and Schmidt, 1978). These cultured cells grow in close connection, projecting pseudopode-like processes into the intercellular spaces. Most nuclei are lobulated. They always are of low electron density with a norrow rim of condensed chromatin confined to the nuclear membrane. One large prominent nucleolus and up to four smaller nucleoli are found. Nuclear pockets in case 1 and deep cytoplasmic invaginations into the nuclear area in both cases frequently occur. In the cytoplasm, besides microtubuli and fibrils, the Golgi apparatus and mitochondria are the predominant organelles. Most mitochondria appear to be dilated containing fragmented cristae. Free ribosomes and polysomal aggregates are randomly distributed. The ratio nucleoplasm:cytoplasm, on the average, is 0.7 in both cases and the cell diameters lie distinctly above those of lymphocytes. At the electron microscope level these cultured monoclonal cells of Hodgkin's disease are not distinguishable from those described in genuine Hodgkin material. Their probable origin and apparent relation to true histiocytic lymphoma cells will be discussed.