In the past, lack of lineage markers confounded the classification of dendritic cells (DC) in the intestine and impeded a full understanding of their location and function. We have recently shown that the chemokine receptor XCR1 is a lineage marker for cross-presenting DC in the spleen. Now, we provide evidence that intestinal XCR1(+) DC largely, but not fully, overlap with CD103(+) CD11b(-) DC, the hypothesized correlate of "cross-presenting DC" in the intestine, and are selectively dependent in their development on the transcription factor Batf3. XCR1(+) DC are located in the villi of the lamina propria of the small intestine, the T cell zones of Peyer's patches, and in the T cell zones and sinuses of the draining mesenteric lymph node. Functionally, we could demonstrate for the first time that XCR1(+)/CD103(+) CD11b(-) DC excel in the cross-presentation of orally applied antigen. Together, our data show that XCR1 is a lineage marker for cross-presenting DC also in the intestinal immune system. Further, extensive phenotypic analyses reveal that expression of the integrin SIRPα consistently demarcates the XCR1(-) DC population. We propose a simplified and consistent classification system for intestinal DC based on the expression of XCR1 and SIRPα.
Keywords: Batf3; SIRPα; XCR1; cross-presentation; dendritic cells.