Gender differences in intestinal immune cell frequencies

Although gender biases in systemic immune responses are described, it is unknown whether immune differences are also present in the intestine. Therefore we studied immune cell populations in Peyer's patches (PP) in male and female mice in two strains. In the spleen and PP frequencies of myeloid (CD11c⁺/CD11b⁺) and lymphoid (CD11c⁺/CD11b^-) DCs and their CD80 and CD103 expression were measured using flow cytometry. In T helper (Th) cells, we measured frequencies of Th1 (Tbet⁺), Th17 (RoRyT⁺) and Treg (FoxP3⁺/CD25⁺) cells. Moreover, the percentage of NKp46⁺ natural killer (NK) cells was determined. Results were tested using 2-way-ANOVA, p<0.05. Faecal microbiota composition was determined using MITchip and ileum gene expression was measured using gene array. Males showed increased CD80⁺ DCs in both PP and spleen and increased CD103⁺ DCs in the spleen. Furthermore, males showed increased Th1 cell frequencies in both PP and spleen and increased Tregs in the spleen. NK cells were decreased in the spleens and increased in the PP of males. Clear gender differences in faecal microbiota composition and small intestinal immunological gene pathways were found. Our results show that gender differences in immune populations, microbiota composition and gene expression can be detected in the intestinal immune system.