ll. MMUNE SYSTEM brief review of the components of the immune system will facilitate an under A standing of the effects of dietary fat on the immune response. The immune system most dispersed network of cells in the body that are not in physical contact yet cooperate functionally. It is composed of both fixed and mobile cells that protec against invading organisms and the development of abnormal (malignant) cells. 1f. however, it overreacts to self, the result is autoimmunity: if it overreacts to nonself. there is an allergic response. Some of these immune cells have very ves but others, which form the basis of immunological memory, exist for many years and perhaps for the lifetime of the host. Fixed cells of the reticuloendothelial system are found primarily in the liver. spleen bone marrow, thymus. lymph node lungs, and intestines. Mobile cells are found throughout the circulation i high num bers, which increase quickly in response to the presence of foreign antigens. It is