Development of an enzyme-linked immunosorbent assay, using a monoclonal antibody against α2-macroglobulin, for the diagnosis of systemic lupus erythematosus

Objectives: To develop an enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody (mab) directed against abnormally glycosylated serum α2-macroglobulin (α2-M) from patients with systemic lupus erythematosus (SLE). Design and methods: Serum α2-M purified by HPLC from patients with SLE was injected in a Balb/c, CB6 F1 female mouse and hybrid cell lines were screened using α2-M Glu-C fragments derived from SLE and normal donors (NHS). A mab was selected and used to develop an ELISA by which sera from NHS (n = 14), SLE (n = 34), rheumatoid arthritis (n = 15), Sjögren’s syndrome (n = 11), mixed connective tissue diseases (n = 12), and liver diseases (n = 11) were analyzed. Results: The affinity of the mab for α2-M from SLE, but not from the other diseases, was higher compared to NHS, as demonstrated by immunoblotting and ELISA. Conclusions: The ELISA was capable of recognizing changes of glycosylation of α2-M in SLE and may be useful for its differential diagnosis.