Blocking IL-10 activity in the Py+Sp co-infection may, similarly to what is seen in the influenza co-infection (van der Sluijs et al., 2004), result in increased levels of inflammatory factors in the respiratory tract, such as TNFα and IFNγ, enhanced PMN infiltration to lungs, and restore the antibacterial immune response to Sp to normal. Here, TNF is linked to coinfection.