Compared with the limited immune response in control siRNA transfected cells, Lyn knockdown led to a significant increase in pro-inflammatory cytokine production, including TNF??, IL-6 and IL-1??, following serum-opsonized Schu S4 infection (Fig. 9C) despite the impaired uptake, providing evidence for a critical role of Lyn in CR3-mediated host immune suppression following Schu S4 infection.