Michopoulos V, Beurel E, Gould F, et al. - Researchers sought to assess the predictive value of peripheral immune factors measured in blood samples taken in an emergency department soon after trauma exposure for later chronic posttraumatic stress disorder (PTSD) development. From a hospital emergency department, they recruited 505 participants who underwent a 1.5-hour assessment. Collection of blood samples was done, on average, about 3 hours after trauma exposure. At 1, 3, 6, and 12 months after trauma exposure, they performed follow-up assessments. Identification of three distinct classes of PTSD symptom trajectories was done: chronic (N=28), resilient (N=160), and recovery (N=85). Individuals in the chronic PTSD class had significantly reduced concentrations of proinflammatory tumor necrosis factor α (TNFα) and interferon-γ (IFNγ) vs those in the recovery and resilient classes. Findings suggest that individuals at risk for developing chronic PTSD in the aftermath of trauma could be identified by assessing the proinflammatory immune response to trauma exposure immediately after trauma exposure in the emergency department.