Th1/Th2 balance: the hypothesis, its limitations, and implications for health and disea... - 0 views
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Matti Narkia on 15 Apr 09Th1/Th2 balance: the hypothesis, its limitations, and implications for health and disease. Kidd P. Altern Med Rev. 2003 Aug;8(3):223-46. Review. PMID: 12946237 Th1 pathways typically produce activation of cytotoxic T lymphocytes (Tc), NK cells, macrophages, and monocytes, all of which can attack cancer cells and generally defend against tumors. 55 IFN-gamma and other Th1 cytokines are typically lower in advanced cancer patients, while the Th2 marker IL-4 can be higher or unchanged.56 Nodules of non-small cell lung cancer freshly removed from patients expressed a marked imbalance toward Th2, as did biopsy samples from basal cell carcinoma.57 In prostate cancer patients IL-2 was low (Th1) and IL-10 high.58 IL-10 is a confirmed Th1-suppressive cytokine, and heightened IL-10 is a common factor in cancer.55 IL-10 has a variety of suppressive effects that include inhibiting Th1 cytokine production, down-regulating APC and NK cell function, and lowering overall T-cell proliferation.57 Especially under the influence of IL-4 (Th2), tumor cells apparently up-regulate IL-10 that suppresses nearby killer cells. Tumor-derived IL-10 has been documented in lymphoma, ovarian carcinoma, melanoma, neuroblastoma, and renal cell and colon carcinoma.57 IL-12 is another cytokine that can be up-regulated by Th1 activity and inhibited by Th2.59 A low IL-12/IL-10 ratio was found in cervical cancer patients.55 Recent clinical studies suggest elevated IL-10 is predictive of a poor prognosis. 57 With both IL-4 and IL-10 being proven inhibitors of Th1 and promoters of Th2 activity, the recognized capability of cancerous tissue to suppress immunity is readily rationalized.
