CCL3 and major depressive disorder: In our own study, we examined the role of pro-inflammatory cytokines in depression across the perinatal period and found increased levels of IL-6 and macrophage inflammatory protein-1 α, chemokine (C-C motif) ligand 3 (MIP-1α/CCL3) beginning in the third trimester and continuing through the early postpartum in more depressed women.