In Vitro Ketamine Attenuates Immune Sensitization in Major Depressive Disorder in a Concentration-Dependent Manner
Yingqian Zhang, Xiaoman Zhuang, Mengqi Niu, Tangcong Chen, Yueyang Luo, Yiping Luo, Abbas Almulla, Andre Carvalho, Michael Maes, Jing Li
medRxiv September 2, 2026 preprint DOI: 10.64898/2026.08.28.26361493 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | In vitro experimental study |
|---|---|
| Sample size | 36 |
| Population | Whole blood from 18 patients with major depressive disorder and 18 healthy controls |
| Intervention | Ketamine |
| Dose | 0.3 μM, 0.6 μM, and 6 μM |
| Duration | 72 hours |
| Topics | Depression Esketamine Ketamine |
| Key findings | The authors report that immune-stimulated blood from patients with major depressive disorder showed elevated immune profiles consistent with immune sensitization, and that ketamine suppressed these responses more broadly in the depression group than in healthy controls, especially at the highest concentration, without normalizing the sensitized phenotype. |
Abstract
Background: Major depressive disorder (MDD) is a severe mental illness associated with severe clinical consequences and substantial societal burden. It’s characterized by immune-inflammatory dysregulation and immune sensitization.
Objective: To determine whether in vitro ketamine attenuates phytohemagglutinin (PHA)/lipopolysaccharide (LPS)-induced immune sensitization in patients with MDD and healthy controls (HCs).
Methods: Whole blood from 18 patients with MDD and 18 HCs was stimulated with PHA/LPS and exposed to ketamine (0.3 μM, 0.6 μM, and 6 μM) for 72 hours. Cytokines, chemokines, growth factors, and composite immune profiles, including M1/M2 macrophages, T helper (Th)1/2/17, the immune-inflammatory response system (IRS), and compensatory immunoregulatory system (CIRS), were synthesized and determined.
Results: Under PHA and LPS stimulation in vitro, the MDD group exhibited markedly elevated immune profiles, including M1, M2, Th1, Th2, Th17, IRS, CIRS, chemokines, and growth factors, consistent with immune sensitization. Significant group × treatment interactions were observed for Th1-Th2, M2, growth factors, IL-12(p70), M1, and chemokines. Ketamine produced minimal changes in HCs but broader suppression in MDD, particularly at the highest concentration, without normalizing the sensitized immune phenotype. Among the immune markers with no notable group × treatment interactions, ketamine exerted diagnosis-independent effects, decreasing MIP-1β, IL-1β, Th1, TNF-β, IRS, IFN-γ, and IL-2 compared to the control condition.
Conclusions: Ketamine exhibited two distinct immunoregulatory patterns: selective, disease-dependent attenuation of sensitized immune pathways and broader, diagnosis-independent suppression of the stimulated immune response, predominantly at higher concentrations. However, these effects were insufficient to normalize the immune-sensitized phenotype of MDD.
Comparable studies
Other preclinical and animal studies on ketamine for depression, most cited first.