Use of Low Concentrations of Human IgA Anti-Tissue Transglutaminase to Rule Out Selective IgA Deficiency in Patients with Suspected Celiac Disease,

Selective IgA deficiency (IgAD) is the most common well-defined primary immunodeficiency disorder in humans (1)(2). Patients with IgAD frequently share the haplotype HLA-DQ2, which is also associated with celiac disease (CD) (3), and therefore have a 10- to 20-fold increased risk of CD (4).High concentrations of anti-tissue transglutaminase (h-tTG) IgA antibody are used to diagnose CD (5)(6), but antibodies are not increased in IgAD (7)(8). This has led to the use of assays for total IgA when testing for CD and/or testing for IgG-class antibodies against h-tTG (9).The aim of our study was to assess whether a second-generation IgA anti-h-tTG assay can detect IgAD, as the concentrations of IgA antibodies would be expected to be very low. This could eliminate the expense for additional tests in many individuals.We studied 4 groups of patients. The disease group included 28 patients with IgAD [18 females (median age, 38 years; range, 8–79 years) and 10 males (median age, 24 years; range, 5–75 years)] diagnosed between June 2001 and May 2003. All had total IgA concentrations 0.05 g/L but below the lower limit of the reference interval (0.70 g/L; median IgA, 0.39 g/L; range, 0.07–0.69 g/L). The final diagnoses in the adult diseased controls were multiple myeloma (30 patients), chronic lymphoid leukemia (4), anemia (4), chronic kidney failure (4), Waldestrom disease (3), acute pulmonary edema (2), scleroderma (1), and acute pericarditis (1). The 14 pediatric patients of this group presented with complaints in relation to …