Cytokine production of RSV/PHA-stimulated tonsillar mononuclear cells: influences of age and atopy.

Links between immune responses to respiratory syncytial virus (RSV), age and atopic sensitisation are poorly understood. This study investigated the induction of target organ type-1, type-2 and proinflammatory cytokine responses to RSV and/or phytohaemagglutinin (PHA) in tonsillar mononuclear cells from children, in relation to age and atopic status. In comparison with the control medium, RSV induced production of the type-1 cytokines interferon (IFN)-gamma and interleukin (IL)-18, the pro-inflammatory cytokines IL-6, -8 and RANTES (regulated on activation, normal T-cell expressed and secreted), but not any of the type-2 cytokines IL-4, -5, -10 and -13. Induction of IL-6, -8 and RANTES, but not IFN-gamma or IL-18, were shown to be dependent on virus replication. PHA induced all except IL-12, -13, and -15. Induction of IFN-gamma, IL-6, -8, and RANTES was significantly increased in atopic children. Induction of both IFN-7 and IL-4 increased in parallel in relation to age, with no change in the IFN-gamma:IL-4 ratio. These data are compatible with the hypothesis that immature type-1 immunity during early childhood plays a role in both respiratory syncytial virus bronchiolitis and in its relationship with atopy.