OBJECTIVETo establish the method of enzyme-linked immunosorbent assay (ELISA) for measuring human IgM autoantibody to folate receptor.

METHODSFolate receptor was extracted and purified from the healthy woman placenta. The protein was coated on 96-well plates with a concentration of 5 ng/Μl. Goat monoclonal antibody was used for detecting antibody. Pooled plasma from healthy donors was used to plot the standard curve and the IgM concentration of pooled plasma was defined as 1. We set up an ELISA procedure to measure human IgM autoantibody to folate receptor. The sensitivity, precision, and stability of the method were evaluated. Further, the folate receptor and bovine folate-binding protein were used as the antigen, respectively, to determine the autoantibody levels in 24 healthy individuals and 20 individuals once gave birth to baby with neural tube defects.

RESULTSThe measuring range of the method was from 6.25 × 10⁻⁴ to 8.00 × 10⁻&sup2;. The lowest IgM level that can be detected was 3.12 × 10⁻⁴. The inter-assay coefficients of variations for samples with high, medium, and low IgM levels were 6.61%,3.50%, and 5.12%, respectively. The intra-assay coefficients of variations were 4.54%, 5.49%, and 5.44%, respectively. The stability test results were considered within acceptable limits. The data from folate receptor-ELISA was significantly higher than that from bovine folate binding protein-ELISA, both in the healthy group (t=-11.9, P<0.001) and in the neural tube defect group (t = 7.35, P<0.001).

CONCLUSIONSThe folate receptor-ELISA method for measuring human IgM autoantibody to folate receptor was successfully established. The method is sensitive, repeatable, and stable.

Autoantibodies ; blood ; Enzyme-Linked Immunosorbent Assay ; methods ; Folate Receptor 2 ; immunology ; Humans ; Immunoglobulin M ; blood

OBJECTIVES: Maternal periconceptional folic acid supplement is by far the most effective primary prevention strategy to reduce the incidence of congenital heart disease (CHD) in offspring. It was revealed that the underlying mechanisms are complex, including a combination of genetic and environmental factors. The purpose of this study is to investigate the association between periconceptional folic acid supplement, the genetic polymorphisms of maternal folic acid receptor 1 gene (FOLR1) and folic acid receptor 2 gene (FOLR2) and the impact of their interaction on the risk of CHD in offspring, and to provide epidemiological evidence for individualized folic acid dosing in hygienic counseling. METHODS: A case-control study on 569 mothers of CHD infants and 652 mothers of health controls was performed. The interesting points were periconceptional folate supplements, single nucleotide polymorphisms (SNPs) of maternal FOLR1 gene and FOLR2 gene. RESULTS: Mothers who took folate in the periconceptional period were observed a decreased risk of CHD [adjusted odds ratio (aOR)=0.58, 95% CI 0.35 to 0.95]. Our study also found that polymorphisms of maternal FOLR1 gene at rs2071010 (G/A vs G/G: aOR=0.67, 95% CI 0.47 to 0.96) and FOLR2 gene at rs514933 (T/C vs T/T: aOR=0.60, 95% CI 0.43 to 0.84; C/C vs T/T: aOR=0.55, 95% CI 0.33 to 0.90; the dominant model: T/C+ C/C vs T/T: aOR=0.59, 95% CI 0.43 to 0.81; and the addictive model: C/C vs T/C vs T/T: aOR=0.70, 95% CI 0.56 to 0.88) were significantly associated with lower risk of CHD [all P<0.05, false discovery rate P value (FDR_P)<0.1]. Besides, significant interaction between periconceptional folate supplements and rs2071010 G→A (aOR=0.59, 95% CI 0.41-0.86) and rs514933 T→C (aOR=0.52, 95% CI 0.37 to 0.74) on CHD risk were observed (all P<0.05, FDR_P<0.1). CONCLUSIONS Periconceptional folate supplements, polymorphisms of FOLR1 gene and FOLR2 gene and their interactions are significantly associated with risk of CHD. However, more studies in different ethnic populations with a larger sample and prospective designs are required to confirm our findings.
Case-Control Studies ; Dietary Supplements ; Female ; Folate Receptor 1/genetics* ; Folate Receptor 2/genetics* ; Folic Acid/administration & dosage* ; Heart Defects, Congenital/genetics* ; Hospitals ; Humans ; Infant ; Polymorphism, Single Nucleotide ; Prospective Studies ; Risk Factors