Dkk1 is induced in activated platelets during acute pulmonary inflammation-associated thrombocytopenia. (A-B) The circulating platelet count in H1N1 influenza virus PR/8-infected, LM-challenged, and live bacteria E coli–infected mice. (C) Platelets were isolated from H1N1 influenza virus PR/8-infected mice (2 dpi) and labeled with PE-CD62P and FITC-CD41 (1 μg/mL of each). Surface expression of CD62P (activation marker) was detected by FACS. (D-F) Protein levels of Dkk1 and CD41 (platelet marker) in circulating platelets in LM-challenged, live bacteria E coli–infected, and PR/8-infected mice were measured by western blot with β-actin as a loading control. Data shown are the mean ± SEM (n = 3-8 animals) and statistical significance is tested by the Student t test. *P < .01 vs control mice.