Abstract: Objective：To establish and evaluate a newly established method of enzyme-linked immunosorbent assay (ELISA) for measuring human autoantibody to folate receptor (FR). Methods: Folate receptor was extracted and purified from healthy woman placenta tissues. The protein was coated on 96-well plates. Goat monoclonal antibody was used as detecting antibody to set up the indirect ELISA procedure. The sensitivity, precision and linearity of the method were evaluated. Further, the method was compared with the ELISA method with commercialized bovine folate binding protein (FBP) by determining autoantibody levels in 24 individuals. Results: The measuring range of the standard curve was from 6.25×10^-4 to 8×10^-2 (the IgG concentration of pooled plasma from healthy donors was defined as 1). The lowest detectable level was 3.13×10^-4. The intra- and inter-assay coefficients of variations were 2.74%-8.07% and 4.16%-8.23%, respectively. Linearity test results were considered within acceptable limits. The data from FBP-ELISA and FR-ELISA were highly correlated (r=0.954, P<0.001); The value from FR-ELISA was higher by 14% than that from FBP-ELISA. Conclusion: The ELISA method for measuring human autoantibody IgG to folate receptor was successfully established using human FR as coating protein. The method is sensitive and repeatable and can be used in large-scale population study.

Key words: Folate receptor, Autoantibodies, Enzyme-linked immunosorbent assay, Immunoglobulin G