CD43 positively regulates T-cell trafficking to lymph nodes. (A-C) T cells from DO.11.10 (WT) or DO.CD43−/− (KO) were stimulated with OVA323-339 and A20 B cells. After 10 to 14 days, resting cells were harvested as described in “Materials and methods.” (A) CD43 expression on KO and WT T cells prior to mixing and injection. (B) WT and KO T cells were mixed in approximately equal numbers and injected into naive BALB/c recipients (n = 8). After 16 hours, blood, spleen, and lymph nodes were examined for the presence of donor CD4 cells by staining for the transgenic DO.11.10 TCR. Contour plots indicating frequency of KO (CD4+CD43−) and WT (CD4+CD43+) T cells in different organs from 1 representative mouse with (bottom panels) and without (top panels) CD43 staining are shown. (C) The bar graph represents the mean (± SEM) of the ratio of the frequencies of KO to WT CD4 T cells in various organs. Data shown are representative of 2 independent experiments with at least 8 mice each (*P < .05). (D) DO.CD43−/− T cells transduced with CD43-FL-GFP or EV-GFP were harvested 10 to 14 days after transduction. Resting cells were mixed in roughly equal numbers and injected into naive BALB/c mice. After 16 hours, the frequency of donor CD4+CD43− (EV) and CD4+CD43+ (FL) CD4 T cells were enumerated in the spleen, lung, and lymph nodes. The bar graph represents the mean (± SEM) of the ratio of the frequencies of EV to FL T cells in various organs. Data shown are representative of 2 independent experiments with at least 4 mice each (*P < .05; **P < .01). (E) Fluorescence intensity of CD62L expression on resting DO.CD43−/− T cells transduced with CD43-FL-GFP or EV-GFP prior to injection. (F) Purified ex vivo T cells from DO.11.10 (WT) or DO.CD43−/− (KO) mice were mixed in approximately equal numbers and injected into naive BALB/c recipients. After 16 hours, blood, spleen, and lymph nodes were examined for the presence of donor CD4 cells by staining for the transgenic DO.11.10 TCR along with CD43. The bar graph represents the mean (± SEM) of the ratio of the frequencies of KO to WT CD4 T cells in various organs. Data shown are combined from 2 independent experiments with a total of 14 mice (ns = not significant).