Fig. 3.

(a)Infection by viable CT renders epithelial cells susceptible to lysis by NK cells. Lysis of SiHa cells by NK cell lines cells following infection with live CT (closed triangles), UV inactivated CT (closed circles) or after mock infection (open triangles). Lysis of K562 (open diamonds) is shown for comparison. The difference between lysis of CT-infected and mock-infected cells is significant (P < 0·001 at effector : target ratios of 10 : 1). Significance was tested using Student's two-tailed t-test. (b) Time-course for the induction of susceptibility to lysis by NK cells following infection with CT. Lysis of SiHa cells by polyclonal NK cell lines at 4, 12 and 22 h following infection with CT (closed triangles) at effector : target ratios from 10 : 1 to 1·25 : 1. Lysis of mock-infected SiHa cells (open triangles) and of K562 (open diamonds) is also shown.