TNF and infection: Using an ex vivo model, Sztein and colleagues have also recently found that direct infection of antigen-presenting dendritic cells with S. Typhi leads to expression of high levels of TNF-α, IL-6 and IL-8, and low levels of interferon-γ and IL-12 p70, but that dendritic cells can also ingest other infected human cells leading to high level expression of interferon-γ and IL-12 p70, with subsequent induction of a population of CD3+CD8+CD45RA-CD62L- effector/memory T cells in co-cultured lymphocytes [53].