HeLa cells demonstrated a marked phagocytic activity towards degenerating cells in their own population after single thymidine blocking. The thymidine treatment caused the high frequency of cell death at the time of thymidine release, but these dead cells were cleared by phagocytosis or autolysis in 7hr after release. Then a prominent increase in the phagocytic activity of non-mitotic cells towards degenerating cells occurred in the mitosis-rich stage 10hr after the release, but this was not associated with a high frequency of cell death.
The non-mitotic cells in this stage had many microplicae and microvilli on their surface, while those in the other stages were relatively smooth in surface morphology. HeLa cells, epithelial in origin, are considered as non-professional phagocytes which retain a primitive phagocytic activity and manifest this function when necessary.