The thymus gland consists of two lobes, it is located behind the breastbone in front of the heart. To a large extent, the health of the thymus determines the health of the immune system. The thymus is a central lymphoid organ where bone marrow derived immature lymphocytes (a type of white cell) undergo differentiation and become active T-cell lymphocytes. They are called T-cells because they primarily mature in the thymus gland, although some also mature in the tonsils. T-lymphocytes, or T-cells, play a central role in cell-mediated immunity. The thymus changes its size and function during our life cycle. It is largest and most active in newborns, infants and in the years prior to adolescence. By the early teens, the thymus begins to shrink, and thymus tissue is replaced by fatty tissue. Nevertheless, a small amount of T-lymphocyte production and education continues throughout adult life. Lymphocytes make up roughly 20 to 40 percent of the total number of white blood cells. Lymphocyte counts drop when bone marrow is suppressed during cytotoxic chemotherapy or radiation therapy. T-cells also decrease when the overall lymphocyte count drops.
The thymus produces enzymes and hormone-like peptides that play an important role in the development, maturation, differentiation, and activation of T-cells. Thymic peptides include thympoeitin, thymulin, thymosin, and thymic humoral factor, which all have both central and peripheral activities. Studies with thymic peptides have shown a variety of effects on the immune system. Basically, thymic peptides act as chemical messengers to activate, regulate, and stabilize the immune system. In clinical trials, thymus peptides strengthen the effects of immunomodulators in immunodeficiency, autoimmune diseases, and neoplastic malignancies.
There are two groups of injectable thymus products available for use in treatment:
Purified extracts from animal (mostly calf) thymus glands which contain peptides (pTE)
Synthetically produced thymus gland peptides (sTP)
Both injectable purified thymus extracts (pTE) and synthetic thymic peptides (sTP) have been demonstrated to enhance the immune system of cancer patients to assist in fighting tumor cell growth and resist infections due to immunosuppression induced by the disease and antineoplastic therapy. There are over 40 different factors in a purified thymus extract, that impart its therapeutic effectiveness, but not all have been adequately researched. For this reason, it is not advisable to only use individual thymus peptides, but rather the entire pTE, or in some cases a combination of the two. There are also oral extract forms of thymus (from bovine sources) in capsules and tablets sold as a dietary supplement.
Generally, pTE has been demonstrated to have the following biological activities:
modulate the production, maturation and activation of T lymphocytes and improve B lymphocyte function
increase the number and function of T helper/inducer lymphocytes (T4 cells)
increase number function of T suppressor cells (T8 cells)
improve immune response through the enhancement of bone marrow function, and protect against bone marrow suppression from cytotoxic chemotherapy and radiation
prevent secondary infections due to immunosuppression caused by cytotoxic chemotherapy and surgical interventions
increase response rate of anticancer therapies through improvement of lymphocyte function and biological defense mechanisms