The immune system is actually affected by several different parts and functions of the body; easy to imagine that the failure of any of these could potentially cause immune problems. In a condensed version of the immune system, these functions include:
Bone Marrow – Manipulates stem cells into B cells as well as being the foundational of other immune cells called “T cells” which upon leaving the bones circulate through the blood stream to any infected site in the body.
Lymph Nodes – Filters tissue fluid for bacteria cells, tumor cells and viral particles
Adrenals – Fights stress which endangers the function of the immune system.
Spleen – Blood filter: removes malignant cells from blood stream.
Thymus Gland – Where cells are developed for maximum efficiency, any cells that cannot provide immune support are destroyed, but healthy, active cells are excreted from the gland into the blood stream.
White blood cells – Responsible for destroying dangerous bacteria, viral and tumor cells, and malignant cells such as parasites (including fungi).
Intestinal Flora – Intestinal flora stimulates the immune system and literally “training” it to prevent the growth of pathogenic bacteria. Therefore it improves function of the mucosal immune system and provides a physical barrier to invading gram-negative bacteria.
As you can imagine, improving any of these functions can aid in the health of the immune system.