MYD88 and infection: In accordance with these histological data, D39 triggered an early and transient neutrophil influx into the lungs of WT mice, as reflected by a marked increase in the number of Ly6+ cells in tissue slides and elevated concentrations of MPO in whole lung homogenates at 6 hours post infection, which was strongly reduced in Myd88-/- mice (Fig. 3A-D, both P<0.0005).