Non-Primate Monocytes - CD14, CD16 - Ziegler-Heitbrock

CD200R family receptors are expressed on porcine monocytes and modulate the production of IL-8 and TNF-alpha triggered by TLR4 or TLR7 in these cells.

Abstract

The inhibitory receptor CD200R1 and its paired activating receptor CD200R1L are involved in the regulation of myeloid cell immune responses. The aim of this study was to analyze their distribution, regulation by cytokines, and function in porcine monocyte subsets. We had previously observed that CD200R1 and CD200R1L genes can generate different protein isoforms through alternative mRNA splicing, therefore in this study, we explored the diversity of transcripts in monocyte subsets, and described several new splicing variants of both CD200R1 and CD200R1L, some of which could be expressed on the porcine monocyte surface. A substantial proportion of CD163-SLAII+ and most CD163+SLAII+ monocytes expressed CD200R1 and CD200R1L receptors, while CD163-SLAII- monocytes did not. CD200R1 and CD200R1L expression was down-regulated in monocytes polarized by IFN-gamma, a cytokine that induces classical activation of macrophages, while IL-10 which gives rise to regulatory macrophages, increased the expression of CD200R1. Finally, treatment of monocyte subsets with a monoclonal antibody specific for the inhibitory CD200R1 receptor and its splicing variants enhanced TNFalpha and IL-8 production, induced by TLR4 or TLR7 stimulation, suggesting a modulatory role for these receptors on porcine monocyte functions.