Lymphocyte subsets and the role of Th1/Th2 balance in stressed chronic pain patients

Background: The complex regional pain syndrome (CRPS) and
fibromyalgia (FM) are chronic pain syndromes occurring in highly
stressed individuals. Despite the known connection between the
nervous system and immune cells, information on distribution of
lymphocyte subsets under stress and pain conditions is limited.
Methods: We performed a comparative study in 15 patients with CRPS
type I, 22 patients with FM and 37 age- and sex-matched healthy
controls and investigated the influence of pain and stress on
lymphocyte number, subpopulations and the Th1/Th2 cytokine ratio in
T lymphocytes. Results: Lymphocyte numbers did not differ between
groups. Quantitative analyses of lymphocyte subpopulations showed a
significant reduction of cytotoxic CD8+ lymphocytes in both CRPS (p
< 0.01) and FM (p < 0.05) patients as compared with healthy
controls. Additionally, CRPS patients were characterized by a lower
percentage of IL-2-producing T cell subpopulations reflecting a
diminished Th1 response in contrast to no changes in the Th2
cytokine profile. Conclusions: Future studies are warranted to
answer whether such immunological changes play a pathogenetic role
in CRPS and FM or merely reflect the consequences of a pain-induced
neurohumoral stress response, and whether they contribute to
immunosuppression in stressed chronic pain patients. Copyright (c)
2008 S. Karger AG, Basel.