Morphology of human T lymphocyte clones

Six human T lymphocyte clones, characterized as to cytolytic activities and several surface markers, were investigated for possible morphologic correlates of function. Cytotoxic T lymphocyte clones and natural killer-like clones had basically similar morphology, but cytotoxic T lymphocytes tended to cluster in groups and had many more lipid bodies, whereas natural killer-like cells had fewer intercellular contacts and had more and larger electron-dense bodies. Dense bodies were also quite prominent in noncytotoxic clones. The latter were distinctive in having a minority of very large cells (10 to 16 microns) with many microvilli, scattered among the majority of 5- to 8-microns diameter cells.