IL2 and major depressive disorder: Interleukin-2 or IL-2R, promoting cell-mediated immunity, was significantly lower in survivors than comparison participants in the current study as in some other studies.15,16,19 However, the current study diverges from the 2004 Tucker study that found selective serotonin reuptake inhibitor (SSRI) treatment increased IL-2R, while at the same time improving subjective measures of PTS and depression to levels of controls;16 in this former study, improvements in subjective measures were consistent with biological markers.