CD16 ligation alone induces IS geometry similar to that of the IS engaging both LFA-1 and CD16. (A) Example confocal microscopy images of YTS-CD16 cells mixed with differentially labeled S2 cells as performed in Fig. 5. Cell outlines are drawn to indicate the perimeter of the conjugate analyzed (yellow, target; red, effector). Quantitative analyses of the total fluorescence intensity of LysoTracker red at the synapse (B), the length of synapse (C), and the percentage of the perimeter of the cell involved engaged in the synapse from the standpoint of the effector (D) or the target (E). Error bars show ± SD. *, P < 0.05; ns, not significant.