Disorders of the Lymphatic and Immune Systems
- AIDS – acquired immune deficiency syndrome – caused by HIV (human immunodeficiency virus) which specifically targets helper T cells; without the helper T cells, the cytotoxic cells and B cells cannot be activated and maintained; the virus invades and reproduces within macrophages
- Elephantiasis – tropical disease caused by roundworms that invade and block lymphatic vessels. As a result lymph accumulates in tissues and leads to swollen “elephant-like” body parts. (Roundworms are contracted through mosquitoes)
- Tonsillitis – inflammation of the tonsils caused by bacteria
- Allergy/Hypersensitivity – abnormally intense immune response to an antigen that may be harmless to most people (these antigens are called allergens)
- o Immediate reaction – occurs when the allergen binds with the IgE antibody in the presence of basophils and mast cells and results in the release of histamines. This stimulates the inflammatory response. The response may be localized (hay fever, hives, allergy-based asthma) which is rarely fatal or systemic (involves the entire body). Systemic responses can be severe and life threatening. May result in anaphylaxis – condition that impairs respiration and can lead to circulatory failure because of a drastic drop in blood pressure. Allergic reactions to penicillin and bee stings may be systemic.
- o Delayed allergic reactions – appear 1 to 3 days after exposure. Caused mainly by cytokines released by sensitized T cells. Poison ivy and certain chemicals cause delayed reactions.
- Autoimmune Diseases – the immune system does not distinguish between self and nonself; antibodies and T cells attack and damage its own tissues
- o Common Autoimmune Diseases:
- Multiple sclerosis (MS) – destroys the myelin sheaths of the brain and spinal cord
- Myasthenia gravis – impairs communication between nerves and skeletal muscles; as a result, muscles are weakened (drooping eyelids, difficulty in swallowing, talking, overall muscle fatigue)
- Type 1 diabetes – destroys pancreatic Beta cells that produce insulin
- Systemic lupus erythematosus (SLE) – systemic disease that affects the kidneys, heart, lungs, and skin
- Rheumatoid arthritis (RA) – systematically destroys joints
- Lymphoma – any tumor of the lymphatic tissue; one type of malignant lymphoma is Hodgkin’s disease – characterized by enlarged lymph nodes, fatigue, fever, and night sweats. Early treatment with chemotherapy or radiation has a high cure rate.