Nasal instillation of gpMBP can exacerbate murine EAE: effect of mucosal priming is an age-dependent phenomenon

Nasal installation or oral feeding of antigens can alter the subsequent immune response in animals and humans. Most mucosal treatments with antigens tend to down-regulate disease, inducing full tolerance or immune deviation; however, priming has also been reported. We evaluated the course of experimental autoimmune encephalomyelitis (EAE) in (SJL x B10.PL)F1 mice after nasal instillation of myelin basic protein. There was a tendency towards exacerbation of subsequent disease in animals if they were nasally exposed to gpMBP during the neonatal period (first week of life), compared to exposure during adulthood. Later, at 11 months of age, this tendency to exacerbate disappeared. Our results suggest that mucosal exposure during early life may regularly modulate the anti-self immune response upwards in individuals genetically predisposed to autoimmune diseases.