The new EUROIMMUN ELISA for detection of soluble CD163 (sCD163) in urine is now available. This is the first CE-certified test for this parameter on the market. Mark Little, Professor for nephrology at the Trinity College in Dublin (Ireland) showed in a study that increased concentrations of sCD163 in urine indicate an inflammation of the glomeruli in the kidneys (glomerulonephritis), which can occur in active ANCA-associated vasculitis (AAV) or lupus nephritis [1].
The protein CD163
CD163 is a membrane protein which is exclusively formed on cells of the immune system, that is, monocytes and macrophages. If there is contact with stimuli which promote inflammation, e.g. bacterial molecules, the CD163 is split enzymatically from the membrane of the immune cells, resulting in soluble CD163. Professor Little and his team suppose the following: In the case of inflammation of the glomeruli, macrophages enter the tissue, which secrete the sCD163 into the urine via the Bowman’s capsules. The biomarker can then be measured in the urine. The more severe the inflammation, more macrophages enter the tissue. Therefore, the concentration of sCD163 provides information on the severity of the glomerulonephritis. The sCD163 level correlates with the disease activity. Correspondingly, the higher the concentration, the more severe is the inflammation.
Application of sCD163-ELISA
The sCD163 ELISA is therefore especially suited for targeted monitoring of patients who have already been diagnosed with AAV with renal involvement. The sCD163 levels, as opposed to systemic inflammation markers, are a specific indicator of renal inflammation and react promptly under treatment or to variations in the inflammatory activity. If regular patient exams yield increased sCD163 levels after a phase of normal values, this may indicate another flare-up of the kidney inflammation. The treatment can now be adjusted at an early stage and the patient saved from irreversible kidney damage.
The sCD163 ELISA complements the current EUROIMMUN product range for diagnostics and/or monitoring of nephropathies. The range encompasses different test methods (indirect immunofluorescence, ELISA, blot, chemiluminescence immunoassays) for the detection of ANCA (ANCA-associated vasculitis), ANA (lupus nephritis), PLA2R and THSD7A (primary membranous nephropathy), as well as the kidney marker uromodulin.
[1] O’Reilly VP et al., J Am Soc Nephrol 27(9): 2906-16 (2016)