The Immune System
Immune Cells: Warriors of the Immune System
Found throughout our body in our blood and tissues are tiny immune warriors called leukocytes (white blood cells) that protect us from injury and infection caused by invading microbes and disease-causing pathogens. Produced in the bone marrow, leukocytes include basophils, eosinophils, mast cells, neutrophils, monocytes, macrophages and lymphocytes. T-lymphocytes leave the bone marrow and mature in the thymus. There are several types of T-lymphocytes produced in the body-- cytotoxic, helper, memory and suppressor T-cells. B-lymphocytes are born and mature in the bone marrow. After activation, B-lymphocytes can become plasma cells that secrete antibodies or memory cells. Some cells within the lymphatic system become antigen-presenting cells (APCs). Macrophages are one type of APC that eat microbial invaders and then display foreign antigens to the CD4+ T helper cells.
Lymph System
Immune cells move throughout the body via the circulatory system (interstate) and the lymphatic system (side streets). The lymphatic system functions in reabsorption of extracellular body fluids and immunity. Lymphatic fluid is filtered in the lymph nodes (immune system headquarters). Immune cells within the nodes filter the lymph and respond to foreign cells or antigens. Disruption of the lymphatic system by parasites (filarial worms) can lead to edema.
