Identification of circulating monocytes as producers of tuberculosis disease biomarker C1q

Abstract

Tuberculosis (TB) is a prevalent disease causing an estimated 1.6 million deaths and 10.6 million new cases annually. Discriminating TB disease from differential diagnoses can be complex, particularly in the field. Increased levels of complement component C1q in serum have been identified as a specific and accessible biomarker for TB disease but the source of C1q in circulation has not been identified. Here, data and samples previously collected from human cohorts, a clinical trial and a non-human primate study were used to identify cells producing C1q in circulation. Cell subset frequencies were correlated with serum C1q levels and combined with single cell RNA sequencing and flow cytometry analyses. This identified monocytes as C1q producers in circulation, with a pronounced expression of C1q in classical and intermediate monocytes and variable expression in non-classical monocytes.

Is the Complement System Dysregulated in Preeclampsia Comorbid with HIV Infection?

“…The first sub-component of the CP, C1q, is an essential part of the complement system. Monocyte-lineage cells, including macrophages, immature DCs, and microglia, are known to locally synthesize C1q, albeit with minor contributions from other cell types [ 70 ]. C1q is a large (460 kDa) glycoprotein whose C-terminal is arranged into a hexameric structure made up of globular heads.…”