Abnormal T-cell reactivities in childhood inflammatory demyelinating disease and type 1 diabetes

Objectives Pediatric‐onset multiple sclerosis offers a unique window into early targets and mechanisms of immune dysregulation. It is unknown whether heightened T‐cell reactivities documented in adult patients, to both target‐organ and environmental antigens, emerge in parallel or develop as early or late events. Our objectives were to determine the presence, pattern, and specificity of abnormal T‐cell reactivities to such antigens in the earliest stages of the multiple sclerosis process. Methods Peripheral T‐cell proliferative responses to self‐, dietary, and control antigens were blindly evaluated in a large cohort of well‐characterized children (n = 172) with central nervous system (CNS) inflammatory demyelination (n = 63), recent‐onset type 1 (insulin‐dependent) diabetes mellitus (T1D; n = 41), nonautoimmune neurological conditions (n = 39), and healthy children (n = 29). Results Children with inflammatory demyelination, CNS injury, and T1D exhibited heightened T‐cell reactivities to self‐antigens, and these responses were not strictly limited to the disease target organs. Children with autoimmune disease and CNS injury also exhibited abnormal T‐cell responses against multiple cow‐milk proteins. Responses to specific milk epitopes distinguished T1D from inflammatory demyelination and other neurological diseases. Interpretation Abnormal T‐cell reactivities to self‐ and environmental antigens manifest in the earliest clinical stages of inflammatory demyelination and T1D. The pattern of heightened T‐cell reactivities implicates both shared and distinct mechanisms of immune dysregulation in the different autoimmune diseases. Abnormal T‐cell responses in children with tissue injury challenge the prevailing view that CNS autoreactive cells inherently mediate the disease in early multiple sclerosis. Ann Neurol 2007