CD4 and colitis: While we cannot present definitive evidence that TREM-1 prolongs neutrophil survival in vivo, we still believe that the reduced presence of neutrophils in Trem1-deficient mice in the CD4 T cell induced colitis and L. major infection model relates to both: A reduced secondary recruitment based on the diminished expression of neutrophil chemotactic mediators and to a reduced life-span in the absence of TREM-1 ligation, with the former mechanism numerically perhaps being more relevant.