Distribution and phenotypes of SLAMF9+ myeloid cells in mouse tissues

Abstract

Abstract SLAM family receptors are critical mediators of immune function, whose expression varies across tissue and cell type. However, the expression of SLAM Family Member 9 (SLAMF9), the most recently discovered protein in the family, has yet to be investigated in mouse or human tissues. In this study, we sought to discover in what tissues and the degree to which SLAMF9 is expressed in the mouse model, as well as determine whether the cells expressing SLAMF9 belong to either a known or a novel subset. We discovered that, within the non-classical monocyte subset (CD45+CD11b+Ly6c-), two broad groups emerged based on SLAMF9 expression. The SLAMF9+ cells in this subset appear to constitute a homogenous group in both the kidney and liver. Renal SLAMF9+ cells also demonstrate higher expression of MHC-II, CX3CR1, and CD11c than their SLAMF9-counterparts, as well as low F4/80 expression and no CD103 expression. However, a cell type with largely similar marker expression and lower frequency appears in the hepatic non-classical monocyte gate, indicating that the cell type may be conserved across tissues. Therefore, SLAMF9 marks a subset of CD103−, CD172a+ classical dendritic cells and may designate a specialized subset of these cells with similar functions in both the liver and kidneys.