Comparison of IgA endomysium antibody and IgA tissue transglutaminase antibody in celiac disease

The antigen for immunoglobulin (Ig) A endomysium antibody (EmA), a sensitiv e and specific serological marker for celiac disease, has recently been des cribed as tissue transglutarninase (tTG). The aim of this study was to comp are the assays used to measure IgA EmA and IgA tTG antibody in patients wit h celiac disease and disease control subjects. Sera from 21 patients with u ntreated celiac disease, 48 patients with seated celiac disease and 128 dis ease control subjects were rested both for IgA EmA with the use of indirect immunofluoresence against human umbilical cord and for IgA tTG antibody wi th the use of ELISA. Titres of IgA tTG antibody were significantly higher in both the untreated and treated celiac groups than in the disease control group. Titres in the treated group were, however, significantly lower than in the untreated grou p. A reference range was calculated to include 99.8% of the disease control group in whom small bowel biopsy showed no evidence of celiac disease. One patient from the disease control group with raised IgA tTG antibody titres and positive IgA EmA was found to have celiac disease on small bowel biops y. The sensitivity, specificity, and positive and negative predictive value s of the IgA EmA assay were all 100%. The sensitivity of the IgA tTG antibo dy assay was 95%, specificity 100%, positive predictive value 100% and nega tive predictive value 97.7%. An ELISA used to measure IgA tTG antibody is an excellent tool to screen fo r celiac disease and may prove useful for monitoring response to treatment.