PSAT118 Elevated Serum IgA at Onset of Type 1 Diabetes in Children

: IgA is the most produced antibody in the body. There are two major forms of IgA, monomeric serum IgA and dimeric mucosal (secretory) IgA. During infection or inflammation, IgA binding to its antigen induces crosslinking of FcaRI, which activates immune effector cells to carry out their functions and can thus induce pro-inflammatory responses, which is hypothesized to occur when IgA titers are high. (1,2) Elevated serum IgA has been associated with autoimmune diseases (3) including type 1 diabetes (T1D) but its role in disease pathogenesis is not well known. To address this gap in knowledge, we aimed to test the hypothesis that at diagnosis of T1D, children and adolescents with elevated serum IgA have different demographic, clinical and laboratory characteristics than those with normal serum IgA. We analyzed 612 children 9.7 [4.2] (mean [SD]) years old (59% Non-Hispanic White, 20% Hispanic, 16% Black, 5% Other) with new onset T1D diagnosed between 1/2008-2/2012 at a large, academic pediatric hospital. Serum IgA values above age-adjusted normal ranges were defined as elevated serum IgA. Patients with low IgA were excluded because of known association between IgA deficiency and autoimmune disease. Demographic and clinical variables were compared between youth with and without elevated serum IgA. Univariable and multivariable regression models were used to compare baseline characteristics that were associated with elevated serum IgA. A significance level of 0.05 was used. We found that elevated serum IgA was present in 21% (128/612) of the children at T1D onset. By multivariate analysis, compared to children with normal IgA, those with elevated IgA were more likely to be of Hispanic ethnicity (Odds Ratio (OR)=3.27, 95% Confidence Interval (CI)=2.00, 5.35) and had a higher hemoglobin A1c (A1c) (OR=1.13, 95% CI=1.01, 1.26). They also had higher odds of having insulin autoantibody (IAA) positivity at diagnosis (OR=1.65, 95% CI=1.10, 2.45) and lower odds of GAD autoantibody (GADA) positivity (OR= 0.57, 95% CI=0.36, 0.93) (all, p<0.05), while there were no significant associations with age, glucose level or presence of DKA. In sum, at diagnosis of T1D, 21% of youth have elevated serum IgA and this was associated with Hispanic ethnicity, higher A1C and positivity for IAA. Our findings suggest that elevated serum IgA may help identify youth with T1D, islet autoimmunity and insulin deficiency. Further studies are warranted to investigate potential pathogenic correlates and persistence over time. This knowledge may lead to new targeted strategies to preserve or improve beta-cell function in individuals with clinical or pre-clinical T1D. REFERENCES: (1) Hansen IS et al. Cell Mol Life Sci. 2019 Mar;76(6): 1041-1055. PMID: 30498997 (2) Leong KW et al. DNA Cell Biol. 2014 Dec;33(12): 823-9. PMID: 25188736 (3) Kerr MA. Biochem J. 1990 Oct 15;271(2): 285-96. PMID: 2241915 Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.