A sandwich ELISA for detection of soluble GPI-80, a glycosylphosphatidyl-inositol (GPI)-anchored protein on human leukocytes involved in regulation of neutrophil adherence and migration--its release from activated neutrophils and presence in synovial fluid of rheumatoid arthritis patients.

GPI-80, mainly distributed on human neutrophils and monocytes, is a novel glycosylphosphatidylinositol (GPI)-anchored protein regulating neutrophil adherence and migration. We prepared a polyclonal antibody specific to GPI-80 by immunizing rabbits with the purified GPI-80 and established a sandwich ELISA for detecting soluble GPI-80. We found that soluble GPI-80 was released from fMLP activated neutrophils and was present at high concentrations in synovial fluids but not sera of rheumatoid arthritis patients, suggesting that GPI-80 may play a role in inflammatory diseases. The detection of soluble GPI-80 may help us to understand its physiological and pathological functions.