Gal-1 promoted agonist-driven positive selection of CD8αα IEL. (A,C,D) The total number of CD8αα (CD8α⁺CD8β^βCD103⁺) IELs from wild-type (n = 4) and gal-1^−/− (n = 4) male H-Y TCR transgenic mice (A); wild-type (n = 6) and gal-1^−/− (n = 6) OT-1 TCR transgenic mice (C); and wild-type (n = 5) and gal-1^−/− (n = 5) C57Bl/6 mice (D). (B) The total number of TCR transgenic positive CD8α⁺CD103⁺ IELs from wild-type (n = 4) and gal-1^−/− (n = 3) female H-Y TCR transgenic mice. More than 75% of CD8α⁺CD103⁺ IEL were CD8β⁻. Each point represents one mouse and was determined by multiplying the percentage of H-Y positive CD8αα, OT-1 positive CD8αα, or C57Bl/6 CD8αα lymphocytes by the total number of isolated IELs for each individual mouse. The horizontal bar represents the mean. For panel A, statistical significance was determined by 2-tailed paired Student t tests. For panels B through D, statistical significance was determined by 2-tailed unpaired Student t tests. P values are listed in the panels.