Identification of ITGA4/ITGB7 and ITGAE/ITGB7 expressing subsets of decidual dendritic-like cells within distinct microdomains of the pregnant mouse uterus

Several leukocyte populations have been described within the pregnant mouse uterus, some of which express the integrin beta 7 (ITGB7). Here we demonstrate that the majority of the ITGB7(+) decidual leukocytes belong to the dendritic cell (DC) lineage. By multiparameter flow cytometric analysis we demonstrated the existence of three distinct DC subsets, characterized by differential expression of ITGA4/ITGB7 (formerly alpha4beta7-integrin) and ITGAE/ITGB7 (formerly alphaEbeta7-integrin). Importantly, the predominant DC subsets reside in distinct microdomains of the Day 9 pregnant mouse uterus. ITGAX(+) ITGAM(med) ITGA4/ITGB7(+) ITGAE(-) (formerly CD11c(+) CD11b(med) alpha4beta7(+) alphaE(-)) cells represent the majority of DCs in the vascular zone (VZ), whereas ITGAX(+) ITGAM(-) ITGAE/ITGB7(+) (formerly CD11c(+) CD11b(-) alphaEbeta7(+)) DCs are mainly located in the lower central decidua basalis (cDB) and the underlying myometrium. A population of ITGAX(+) ITGAM(low) DCs lacking ITGB7 are restricted to the cDB. Confocal microscopy studies show direct contact of VZ DCs with uterine natural killer (uNK) cells, suggesting a functional relationship between both cell populations. Collectively, our data identify three phenotypically distinct DC subsets residing in distinct microdomains of the uterus. The differential expression of ITGA4/ITGB7 and ITGAE/ITGB7 suggests distinct functional roles of the different DC subsets during early pregnancy.