Altered synthesis of interleukin-12 and type 1 and type 2 cytokinesin rhesus macaques during measles and atypical measles.

Immunosuppression during and after measles results in increased susceptibility to other infections and 1 million deaths annually. The mechanism by which measles virus (MV) induces immune suppression is incompletely understood, but a type 2 skewing of the cytokine response after infection has been documented. In vitro studies suggest that lack of interleukin (IL)-12 production by monocytes and dendritic cells plays an early role in the skewed response. In addition, immunization with an inactivated measles vaccine before measles develops appears to lead to an even stronger type 2 skewing of the cytokine response and atypical measles. In this study, the cytokine responses in rhesus macaques were compared after vaccination with live and formalin-inactivated vaccines and after challenge with MV. In vivo production of IL-12 was decreased during the viremic phase of the illness, and production of IL-4 was increased during and after atypical measles, compared with measles.