Enzyme-linked immunosorbent assay (ELISA) is an excellent tool for detection of circulating antibodies against the NC16A portion of BP180 antigen. We compared the sensitivity and specificity of a commercially available BP180-NC16a domain ELISA with that of an indirect immunofluorescence (IIF) testing in the evaluation of bullous pemphigoid (BP) and pemphigoid gestationis (PG), and analyzed the relationship between ELISA results and the presence of IgG deposition, in an epidermal or combined pattern, on direct immunofluorescence (DIF) testing of salt-split skin. ELISA was performed on serum from 28 patients (24 BP, 4 PG) and 50 controls. IIF testing was performed on serum from 27 patients and 98 controls. For the group of 28 patients with BP or PG, ELISA had a sensitivity of 93% and specificity of 96% (P < 0.001), while sensitivity was 74% and specificity 96% (P < 0.001) for IIF testing. In these patients, ELISA has a higher sensitivity than IIF testing, but similar specificity. Evaluation of controls who had IgG deposition on the dermal side of salt-split skin on DIF testing showed specificity for the ELISA of 100% (all four cases negative) and 80% for IIF testing (one of five positive). Positive ELISA correlated with a diagnosis of BP or PG only in patients who had IgG at the basement membrane zone (BMZ) by DIF testing. Overall, ELISA appears to have greater sensitivity and specificity for BP or PG than does IIF testing.

Therapeutic strategies should not be based exclusively on anti-Dsg antibody values. Anti-Dsg1 antibodies showed a closer relationship with skin activity than IIF, while anti-Dsg3 antibodies showed a relationship with mucosal activity similar to the IIF test.

RATIONALE: Egg is the second most common food allergen in childhood and the most important one in children with moderate-to-severe atopic dermatitis (AD). Despite this fact, few are the Brazilian data regarding epidemiology, clinical features and natural history of EA in our population. The aim of our study was to analyze clinical and epidemiological features of EA children. METHODS: Review of electronic charts from patients followed from July, 2017 to July, 2018. Patients over 18 y/o were excluded from the study. RESULTS: 135 children with food allergy (FA) were evaluated. Egg was the second most common food allergen in this population (36 patients, 26,6%), following cow's milk (85%). EA was more prevalent in male sex (1,6:1). The mean age of onset of symptoms was 6 months and at diagnosis was 35 months (delta 29m). 50% of the patients presented with immediate IgE-related features, 11% presented with delayed reactions and 39% referred both symptoms. 33 (93%) of the patients have at least one other allergic disease (now called multimorbidity) and 86% have other FA. 9 patients (25%) developed tolerance during the year, with mean age of 55 months, none of them had history of severe reactions. 27 (75%) persist with EA (mean age-76 months). CONCLUSIONS: EA is the second most prevalent cause of FA in our population, following the data of most FA prevalence surveys. EA prognosis is considered good, and most children develop tolerance up to 60 months. High rates of multimorbidity and other FA were observed. J ALLERGY CLIN IMMUNOL FEBRUARY 2019 AB278 Abstracts MONDAY