Immune cells in the mouse lungs. (a–d) Light microscopic photographs showing immunohistochemical staining of the mouse lungs with CD3 (a), B220 (b), Iba1 (c), and Gr1 (d). Immunopositive cells (indicated by arrows) are present in the lungs of MRL/MpJ, MRL/MpJ‐lpr, BXSB/MpJ and BXSB/MpJ‐Yaa mice, and their appearance differs between the strains. In particular, the MRL/MpJ‐lpr and BXSB/MpJ‐Yaa mice show a greater abundance of positive cells within the infiltration area. Bars = 50 μm (a–d). Graph showing the average density of CD3‐positive (a), B220‐positive (b), Iba1‐positive (c), and Gr1‐positive (d) cells/unit area in all the lobes in the lungs of MRL/MpJ, MRL/MpJ‐lpr, BXSB/MpJ and BXSB/MpJ‐Yaa mice (e). Statistically significant difference, as determined using the Mann–Whitney U‐test; n = 5 mice for each strain, between autoimmune disease models (MRL/MpJ‐lpr and BXSB/MpJ‐Yaa) and the control strains (MRL/MpJ, BXSB/MpJ), respectively, is indicated by asterisk (*P < 0·05). Values are shown as the means ± SE.