Immunological differences between patients with major depression and somatization syndrome

Area of Science:

• Immunology
• Psychiatry
• Neuroscience

Background:

• Major depression is linked to inflammatory response system (IRS) activation.
• Proinflammatory cytokines and IRS activation are associated with sickness behavior in animal models.
• The IRS in somatization disorder remains unexamined.

Purpose of the Study:

• To investigate immunological differences between major depression, somatization disorder, and healthy controls.
• To assess inflammatory response system variables in these groups.

Main Methods:

• Measured IRS variables: interleukin-6 (IL-6), interleukin-1-receptor-antagonist (IL-1RA), soluble IL-6 receptor (IL-6R), soluble CD8, leukemia inhibitory factor receptor (LIF-R), and Clara cell protein (CC16).
• Included patients with major depression (n=36), somatization syndrome (n=37), comorbid depression and somatization (n=40), and healthy controls (n=37).

Main Results:

• Increased serum CD8 in major depression compared to somatization disorder; intermediate in controls.
• Lower serum CC16 in major depression versus controls; highest in somatization disorder.
• Lower serum IL-6 in somatization disorder compared to controls and major depression.

Conclusions:

• Depression exhibits IRS activation with T-cell (CD8) and monocytic (IL-1RA) activation, and reduced anti-inflammatory capacity (CC16).
• Somatization disorder shows monocytic activation (IL-1RA) and reduced T-lymphocyte activity (CD8, IL-6).
• Distinct immune alterations characterize somatization disorder and major depression.