Table 2.

Potential biomarkers in peripheral blood for antidepressant-treatment outcomes

Cytokine	Serum level of cytokine in MDD vs controls	Results of treatment outcome	Reference(s)
IL6	Baseline increased	Resistant to treatment	83–85
	Increased	Significantly reduced by escitalopram and nortriptyline	86
	—	Escitalopram had no effect	87
	Increased	Fluoxetine had no effect	88
IL11	No known difference	Reduced by escitalopram	87
IL1β	Increased	Significantly reduced by escitalopram and nortriptyline	86
	—	No change with 8 weeks’ escitalopram	87
TNF	Baseline increased	Poor response to amitriptyline	8
	Baseline increased	Poor response to SSRIs	16, 89
	Baseline increased	Serum levels negatively correlated with response	84, 89

Abbreviations: MDD, major depressive disorder; SSRI, selective serotonin-reuptake inhibitor.