Ultrastructure of lymphocyte tumor cell interaction with localization of cell-bound antibody by ferritin labeling.

Splenic lymphocytes derived from Walker carcinoma-bearing rats were harvested and incubated with Walker carcinoma cells growing in tissue culture. The sequence of events leading to target cell death was studied by phase microscopy and scanning and transmission electron microscopy. The sensitized lymphocytes adhere to the tumor cells by multiple cytoplasmic appendages, but no ultrastructural changes are seen at this interface. After 1 hr these lymphocytes release cytoplasmic components consisting of membrane-lined vesicles, cell membranes, endoplasmic reticulum, and cytoplasmic material. This material adheres closely to the surface of the tumor cells and is subsequently seen within the cytoplasm of the tumor cell. The tumor cells then undergo degenerative changes and cell death occurs in 24 to 36 hr. The lymphocyte-derived material appears to contain immunoglobulin components as determined by specific ferritin labeling.