Two novel sandwich ELISAs identify PAD4 levels and PAD4 autoantibodies in patients with rheumatoid arthritis

Objective The peptidylarginine deiminase 4 (PAD4) gene and PAD4 autoantibodies have been associated with rheumatoid arthritis (RA) and its pathogenesis. Therefore, methods for accurately determining their levels in the peripheral blood of these patients would be a diagnostic asset. The objective of our study was to adapt the enzyme-linked immunosorbent assay (ELISA) method for evaluating PAD4 levels in human blood.