CD28- and TCR-mediated signals exert independent effects on T-cell migration. Male (A-C) and female (D-F) C57BL/6 mice were coinjected intravenously with HY-specific CD28-triggered (PKH26 labeled) or control (CFSE labeled) T cells 48 hours after receiving 600U IFNγ. A representative image (scale bar: 30 μm) and the mean T-cell infiltration of the peritoneal membrane, assessed as specified in “Materials and methods,” are shown. (C,F) Representative histograms and average number (+SE) of labeled T cells in the peritoneal lavage of at least 3 mice that received either PBS (top histograms and autofluorescence bars) or T cells 24 hours earlier are shown. (A, *P < .01; C, *P < .05; D, *P < .003; F, *P < .005).