Assessment of complement cascade components in patients with major depressive disorder.
Brain, behavior, and immunity July 1, 2025 Brandi Quintanilla, Dede Greenstein, Ashutosh Tripathi et al. 7 citations
Ketamine, a rapid-acting antidepressant, may also regulate immune function. The complement system, part of the innate immune response involved in synaptic plasticity, has been linked to depression. This analysis of data from 39 people with major depressive disorder and 25 healthy volunteers, originally part of a randomized, double-blind trial comparing intravenous ketamine (0.5 mg/kg) to placebo, measured plasma levels of complement proteins C3a and C4a at baseline, 230 minutes, Day 1, and Day 3. A significant interaction between diagnosis and sex was found for C3a but not C4a levels. Ketamine's effects on C3a and C4a did not change over time. The findings suggest that targeting the complement pathway could lead to advances in treating major depressive disorder.