Because we noted a significant increase in the absolute numbers of CD4+ T cells in patients with PTSD (Figure 2B), we next determined if they were T helper Th1, Th2, Th17 or Treg cells based on intracellular staining for IFN-γ, IL-4, IL-17 or FoxP3 respectively. Here, IFNG is linked to post-traumatic stress disorder.