Table 1.

Cytotoxic T lymphocytes change from perforin-expressing to perforin-deficient cells in vitro

	0 hr		48 hr		Survived
Cells	×106	(%)	×106	(%)	(%)
CD8+ cells	162	–	60	–	37
Perforin-positive	116	72	19	31	16
Perforin-deficient	45	28	41	61	91