Peripheral blood cellular immunophenotype in depression: a systematic review and meta-analysis

Area of Science:

• Immunology
• Psychiatry
• Cell Biology

Background:

• Meta-analyses suggest immune dysfunction in depression, evidenced by elevated cytokine levels.
• White blood cells (WBCs) are crucial for immune responses, but their specific role in depression remains unclear.
• A systematic review is needed to understand WBC subset alterations in depression.

Approach:

• A systematic review and meta-analysis were conducted using PubMed and PsycINFO databases.
• Studies comparing flow cytometry-derived WBC subsets in depression cases versus controls were selected.
• Random-effect meta-analysis was performed on 27 studies involving 2277 participants.

Key Points:

• Increased mean absolute counts of WBCs, granulocytes, neutrophils, monocytes, CD4+ helper T cells, natural killer cells, B cells, and activated T cells were observed in depression.
• Fewer studies reported relative percentages, but indicated increased neutrophils and decreased total lymphocytes, Th1, and Th2 cells.
• Significant heterogeneity was noted in several analyses (e.g., neutrophils, natural killer cells, B cells).

Conclusions:

• Depression is associated with widespread changes in circulating myeloid and lymphoid cells, indicating immune dysfunction.
• These immune cell alterations suggest a role for both innate and adaptive immunity in depression.
• Immune cells may serve as valuable biomarkers for depression subtyping and patient stratification in future immunotherapy trials.