H5 influenza haemagglutinin and cytokine profiles in cultured PBMCs from adults and children

Summary Objective As reported by WHO in its most recent report, H5N1 influenza virus affects mostly children. Differences in morbidity depending on the age could be explained, at least in part, by the differences in the immune response between children and adults. The main objective of the study was to evaluate the effect of H5N1 influenza haemagglutinin on the cytokine secretion profiles of peripheral blood mononuclear cells (PBMCs) from both children and adult healthy donors. Materials and methods We compared the profiles of 19 cytokines and chemokines released after exposure to PBMCs obtained from 30 healthy children and 30 healthy adults to a recombinant glycosylated H5 haemagglutinin after 24 h of culture with this antigen, compared to untreated control cells. Results Donors had not been exposed previously to the virus, as evidenced by the absence of haemagglutination inhibition activity in their plasma samples. Direct contact of PBMCs from both children and adults with the haemagglutinin of H5N1 virus induced increased levels of IL-6, MCP-1 and MIP-1β in the culture supernatants compared to control. Supernatants of adult PBMCs also showed increased levels of IL-8 and IP-10. Conclusions The results of our study supports the idea that, in the absence of protective immunity, the haemagglutinin of the H5N1 virus is able to induce the release of pro-inflammatory mediators by direct contact with PBMCs. Some of these mediators (IL-6, MCP-1 and MIP-1β) are induced regardless of age and have been previously reported to be associated with a poor control of viral replication in severe patients and animal models.