IgA- and IgG-Class Antihuman Umbilical Cord Antibody Tests in Adult Coeliac Disease

Abstract

Background: An antiendomysium antibody test using human umbilical cord as antigen has recently been introduced. Methods: We determined IgA- and IgG-class antihuman umbilical cord (HUC-ab), antireticulin (ARA), and antigliadin antibodies (AGA) in 92 untreated adult coeliac patients, in 95 non-coeliac subjects, and in 4 coeliac patients with selective IgA deficiency. Tissue antibodies were measured with an indirect immunofluorescence method and AGA with an enzyme-linked immunosorbent assay. Results: Of adult coeliac patients 85% were positive for IgA-class HUC-ab, 78% were positive for ARA, and 80% for AGA; the specificity for HUC-ab and ARA was 100%, and for AGA 86%. Combination of HUC-ab, ARA, and high-titre AGA increased the sensitivity to 96% without loss of specificity. IgG-class HUC-ab was positive in 12% of coeliac patients, in all four coeliac patients with IgA deficiency, and in none of the controls. Conclusions: The HUC-ab test is highly specific but not 100% sensitive for detecting adult coeliac disease. A combination of the IgA-class HUC-ab, ARA, and high-titre AGA tests is recommended. In selective IgA deficiency the IgG-class HUC-ab test seems to work well.