S78 A distinct immune regulatory receptor profile linked to altered monocyte subsets in sarcoidosis

Introduction and Objectives In sarcoidosis, blood monocytes display enhanced inflammatory responses, reduced expression of the regulatory receptor CD200R, and altered subsets defined by CD14 and CD16. We investigated the relationship between sarcoidosis monocyte subsets and expression of CD200R and other regulatory receptors. Methods We studied live monocytes from 25 treatment-naive patients with pulmonary sarcoidosis and age-matched healthy controls. Results Non-classical monocytes were expanded in sarcoidosis and exhibited significantly lower expression of CD200R, SIRP-α, and CD47 than classical or intermediate monocytes. All sarcoidosis monocyte subsets had significantly reduced CD200R and CD47 expression compared with healthy controls. Conclusions We provide the first description of significantly reduced regulatory receptor expression on non-classical monocytes. Expansion of these non-classical monocytes in sarcoidosis, together with reduced levels of specific regulatory molecules (CD200R and CD47) on all sarcoidosis monocyte subsets compared with controls, will favour heightened inflammatory responses. This sarcoidosis monocyte phenotype could be assessed as a prognostic or therapeutic biomarker in future studies.