Final answer:
Acupuncture is the complementary and alternative therapy known to alter immune function by potentially stimulating various immune responses, including anticancer responses and modulation through the HPA axis and sympathetic nervous system.
Step-by-step explanation:
The complementary and alternative therapy that is known to alter immune function is acupuncture. Acupuncture is a form of alternative medicine primarily used for pain relief but also believed to affect immune function. During an acupuncture treatment, fine needles are inserted into the body at specific points. While acupuncture is generally safe when performed by a trained professional, there is a theoretical risk of exposure to pathogens if the needles are not properly sterilized.
Beyond the potential for exposure to pathogens through improper needle use, acupuncture is thought to modulate the immune system. This form of alternative medicine may stimulate various immune responses, including the activation of cytotoxic T cells, which play a role in anticancer responses. The procedural stress of acupuncture may also stimulate the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system, both of which are known to innervate immune organs and may influence immune function either positively or negatively.