Anergic T cells inhibit tissue infiltration in vivo. Male CBA mice were injected intraperitoneally with 600 U IFN-γ. As a negative control, untreated female mice were used (panels A,E). Two days later, mice received an intraperitoneal injection of either PBS (panels A-B,E-F), responsive (3-5 × 10⁷; panels C,G), or anergic (3-5 × 10⁷; panels D,H) B9 CD4⁺ T cells (4 × 10⁶/mouse). After 24 hours, red fluorescence-labeled (PKH26) HY-specific C6 T cells (5 × 10⁷) were also injected intraperitoneally in all the mice. The following day, the presence of fluorescently labeled cells in the peritoneal membrane (× 10 original magnification; panels A-D) and in the peritoneal lavage (panels E-H) was assessed by wide-field fluorescence microscopy and flow cytometry, respectively. The peritoneal membrane wide-field images and histograms (in which the percentage of positive cells is specified) are taken from a representative experiment; however, the median number and range of labeled cells quantified in 10 randomly selected × 40-magnified fields of the peritoneal membrane of at least 3 different animals are shown below each image (panels A-D). Similarly, the median percentage of labeled cells recovered in the peritoneal lavage of 3 different samples is specified below each representative histogram. * indicates statistically significant (P < .0001, panel D; P = .05, panel H) compared with male CBA mice (positive control).