Th1/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.
True to form, Dr. John Cannell has published yet another wonderfully insightful Vitamin D Newsletter.
One item caught my eye, a response to a question about the Marshall Protocol. I, like Dr. Cannell, was inundated with questions about this so-called protocol, which amounts to little more than the unfounded speculations of a non-physician, actually someone not even involved in health care.
In all honesty, I blew the whole issue off after I read Dr. Marshall's rants. They smack of pure quackery, though from somebody who clearly has a command of scientific lingo. To Dr. Cannell's credit, he took the time and effort to construct a rational response in the latest issue of the newsletter. I reproduce his response here:
Zwart SR, Hargens AR, Smith SM.
The ratio of animal protein intake to potassium intake is a predictor of bone resorption in space flight analogues and in ambulatory subjects.
Am J Clin Nutr. 2004 Oct;80(4):1058-65.
PMID: 15447920