Rapid Reagin Reaction (RRR)
RRR (rapid reagin reaction) or RPR (rapid plasma reagin) is a screening test for syphilis detection and confirmation. RRR is a microflocculation reaction where the antigen- cardiolipin is mixed with cholesterol and lecithin. Cardiolipin is a phospholipid (hapten) contained in the membrane of Treponema pallidum, but also in other bacteria and also in mitochondria.
Antibodies against cardiolipin produced during syphilis are called „reagins“. Clusters form when the antigen encounters antibodies. RRR might be false positive, therefore positivity needs to be confirmed, e.g. by TPHA (Treponema pallidum hemagglutination test).