Normal primary immune response in Clec1b^−/−PF4-Cre adult mice. (A) CD45.1⁺ SM1 cells (10⁵) were transferred into CD45.2⁺Clec1b^fl/flPF4-Cre and Clec1b^fl/fl mice, which were immunized the following day with ∼20 μg of alum-precipitated FliC peptide in the front paw pad. After 7 days, numbers of CD45.1⁺ SM1 T cells were analyzed in draining and nondraining contralateral brachial LNs. (B) Macroscopic appearance of draining (left) and nondraining (right) LNs from Clec1b^fl/flPF4-Cre (top) and Clec1b^fl/fl (bottom) littermates. (C) Flow cytometric analysis on the single-cell suspensions of the draining (first row) and nondraining (second row) brachial LNs of Clec1b^fl/fl control and Clec1b^fl/flPF4-Cre littermates showing CD45.1⁺CD3⁺ SM1 cells. Percentages of CD45.1⁺CD3⁺ SM1 cells are indicated in the dot plots. (D) Chart showing the number of SM1 cells in the draining and nondraining brachial LNs of Clec1b^fl/flPF4-Cre and Clec1b^fl/fl littermates. Two-tailed Mann-Whitney test, *P < .05, **P < .01. (E) Mice were immunized with PE cells in the front paw pad. After 7 days, numbers of PE⁺ B cells and GC B cells were analyzed in draining LNs. (F) Chart showing the number of PE⁺B220⁺ B cells and PE⁺ B220⁺GL7⁺CD38⁻ GC B cells (left) and the percentages of GC B cells in the B-cell populations (right) in the draining brachial LNs of Clec1b^fl/flPF4-Cre and Clec1b^fl/fl littermates. Unpaired Student t test; ns, nonsignificant. (G) Immunofluorescence analysis of sections of the draining LNs of Clec1b^fl/flPF4-Cre and Clec1b^fl/fl littermates mice stained with DAPI in gray and for IgD in green, PE in red, and CD3 in blue.