Dendritic cells in SPPL2a−/− and SPPL2a/b double-deficient mice. (a) The levels of full-length CD74 and the CD74 NTF were determined in LPS-stimulated BMDCs from wild type, SPPL2a−/−, SPPL2b−/−, and SPPL2a/b double-deficient (Do-ko) mice by Western blotting. SDS-PAGE with a standard Tris-glycine buffer system was used for electrophoretic separation. Isoforms (p31 and p41) of full-length CD74 and the CD74 NTF accumulating in SPPL2a−/− and SPPL2a/b double-deficient cells are indicated by filled and open arrowheads, respectively. (b and c) CD11c and MHC-II double-positive cells were quantified by flow cytometry in spleens (b) or lymph nodes (c) of wild-type, SPPL2a−/−, SPPL2b−/−, and SPPL2a/b double-deficient mice. Graphs show the mean absolute number of these cells (CD11c+ MHC-II+) in the spleen (b) or in lymph nodes (c) quantified as the means ± the SD in 6 mice per genotype. ***, P < 0.001; **, P < 0.01; *, P < 0.05 (one-way ANOVA with Bonferroni post hoc testing).