Expansion of CD4 T Lymphocytes Expressing Interleukin 17 and Tumor Necrosis Factor in Patients with Major Depressive Disorder.

BACKGROUND

We have investigated the distribution of the Th1, Th2 and Th17 subsets in circulating CD4 T lymphocytes and their naïve (T), effector (T), central (T) and effector memory (T) activation/differentiation stages in patients with major depressive disorder (MDD).

METHODS

Thirty MDD patients and 30 healthy controls were studied. The counts of circulating CD4 T lymphocytes and their distribution on the T, T, T and T activation/differentiation stages were analyzed by polychromatic flow cytometry. The intracytoplasmic interferon gamma (IFNγ), interleukin (IL)-4, IL-17A and tumor necrosis factor alpha (TNF-alpha) and membrane CD28 expression were also measured. The serum IFNγ, IL-4, Il-17A and TNF-alpha were measured by Luminex, respectively.

RESULTS

MDD patients had normal counts of CD4 T lymphocytes and of their T, T and T subsets but increased number and percentage of T CD4 subset. CD4 T lymphocytes had significantly enhanced percentage of cells that express IL-17 and TNF-alpha explained by the expansions found in the T, T and, T and T, T and T activation/differentiation stages, respectively. A selective increase in the percentages of T and T expressing IFNγ was also observed. We found a significant correlation between the percentages of CD4 T lymphocytes expressing IFNγ and TNF-alpha in these patients. MDD patients showed increased serum levels of IL-17 and TNF-alpha, but normal IFNγ and IL-4 concentration.

LIMITATIONS

the cross-sectional nature of the study could be considered a limitation.

CONCLUSIONS

MDD patients have abnormal circulating CD4 T lymphocytes with expansion of the IL-17 and TNF-alpha expressing cells as well as increased levels of circulating IL-17 and TNF-alpha.