Rejection of Tumor Cells <i>in vitro</i>: Morphological Studies on Killer T Cells and Damaged Tumor Cells

Abstract

The in vitro destruction of a methylcholanthrene-induced guinea pig sarcoma (MC-D) by killer T lymphocytes was investigated by light and electron microscopy. Various degrees of cell damage ranging from slight to extensive were observed. In cells with slight injury, dilatation, vesiculation, fragmentation and degeneration of the rough surfaced endoplasmic reticulum were the most characteristic findings. In cells with extensive injury, widespread nuclear and cytoplasmic alterations were evident and many of these cells were fragmented into smaller portions and finally transformed into granular membranous and amorphous debris. Cytoplasmic vacuoles filled with electron-lucent material were frequent in extensively damaged cells. Killer lymphocytes resembled closely antibody-forming plasma cells when examined with light microscopy but lacked the extensive network of rough surfaced endoplasmic reticulum, and did not produce immunoglobulin. It is suggested that these extensively differentiated T-derived killer cells are end cells similar to those of B lymphocyte-derived plasma cells. Viral particles resembling closely C-type viruses were observed in mixed killer cell MC-D cultures.