Differential effects of laughter on allergen-specific immunoglobulin and neurotrophin levels in tears.

Laughter after viewing a humorous video "Modern Times" decreased Japanese cedar pollen-specific immunoglobulin E (IgE) and IgG4 levels, while it enhanced Japanese cedar pollen-specific IgA levels in tears of patients with atopic keratoconjunctivitis, while viewing a nonhumorous weather information video did not do so. Laughter after viewing "Modern Times" also decreased nerve growth factor levels without affecting neurotrophin-3 levels in tears of those patients, while viewing a weather information video did not. These results indicate that laughter decreased allergen-specific IgE and IgG4 production and increased allergen-specific IgA production with concomitant decrease in nerve growth factor. These results indicate that laughter may have some implications for study and treatment of allergic diseases.