Induction of tumor necrosis factor-α (TNF-α) by Staphylococcus aureus L-form was investigated. The supernatant of a macrophage culture mixed with S. aureus L-form showed a potent cytotoxic activity to L cells. Addition of anti TNF-α antibody inhibited completely the cytotoxic activity of the supernatant, indicating that the activity might be due mostly to TNF-α. To investigate localization of TNF-α production, the membranes of hypotonicity treated L-form were layered on a step-gradient composed of an upper and lower layers of 35% and 50% sucrose, respectively. The membranes were banded at the interface of 35% and 50% of sucrose. The activity of TNF-α production of the membrane fraction was 10-times higher than that of the soluble fraction.
