TNF and pneumonitis: To study whether the severity of pneumonitis was associated with elevated pro-inflammatory cytokines and chemokines in infected pregnant mice, levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), interferon-γ (IFN-γ), macrophage inflammatory protein (MIP)-1α, MIP-2 and tumor necrosis factor-α (TNF-α) in the lung homogenates of infected mice were tested by ELISA.