ObjectivesTo detect the presence of antibodies against bovine serum albumin in a cohort of Spanish patients with type 1 insulin-dependent diabetes.MethodsAntibodies were measured using an in-house enzyme-linked immunosorbent assay test in 80 patients with type 1 diabetes, subdivided according to the presence or absence in their serum of celiac disease-related antibodies. For comparison, 30 patients with celiac disease (nondiabetic), 13 patients with autoimmune thyroiditis, and 45 healthy volunteers were used.ResultsThirty-one percent of patients with diabetes yielded a positive result, with a mean value of 26.1 ± 21.8 arbitrary units (AU). If the group was split into those with celiac disease-related antibodies and those lacking them, the percentages were 53% and 25%, respectively, with a mean value of 39.6 ± 28.4 AU and 22.4 ± 18.3 AU (P= 0.003), respectively. Seventy-three percent of celiac patients showed bovine serum albumin antibodies with a mean level of 38.8 ± 27.7 AU, comparable to that of patients with diabetes with celiac antibodies, but higher than the group lacking them (P= 0.001). Although 46% of patients with autoimmune thyroiditis had positive results, the level detected (22.1 ± 8.7 AU) was significantly lower than that recorded in patients with type 1 diabetes who had celiac disease antibodies (P= 0.04) and celiac patients (P= 0.04). Healthy volunteers showed no antibodies against bovine serum albumin.ConclusionsThese data suggest that bovine serum albumin antibodies appears in patients with a compromised epithelial permeability, and they reflect a general defect in the process of immunologic tolerance associated with a predisposition to autoimmunity, rather than immunity specific to &bgr; cells.