Medical Terminology: The Immune System

1. What is The Immune System?
Normal functioning of the immune system protects the body against the invasion of outside organisms. A variety of organisms are capable of this; however, not all are harmful. The cells of the immune system recognize organisms that invade the body, then isolate and destroy them.
At times, the immune system is not able to adequately function in this capacity. This results in infection, immunodeficiency disorders, autoimmune disorders, allergies, and hypersensitivity reactions. Lymphocytes are the primary cells of the immune system.
Lymphocytes are divided into B cells and T cells. B cells provide a humoral immune response (antibodies), because they produce an antigen-specific antibody. T cells provide a cellular immune response. Mature T cells are composed of CD4. and CD8. cells. CD8. cells are responsible for destroying foreign and viral inhabited cells, and suppress immunologic functions. CD4. cells, also known as T-helper cells, stimulate immune functions, such as B cells and macrophages. A macrophage is a cell whose functions include ingesting foreign or invading cells.

2. Acquired Immunodeficiency Syndrome (AIDS)
The human immunodeficiency virus (HIV) causes malfunction of T cells, which protect the body from invading microorganisms. When it enters a cell, HIV replicates, causing the cell to reproduce more infected cells. It also frequently causes cell death. The CD4. lymphocyte is most often affected, followed by B lymphocytes and macrophages. Immunodeficiency results.

3. Anaphylaxis
An allergen, usually food or medication, enters the body causing the release of histamines, resulting in capillaries dilating and smooth muscle contracting. This causes edema, respiratory distress, hypotension, and skin changes, leading to an allergic reaction. Lesser degrees of extreme allergy are urticaria (hives) and angioedema (swelling caused by exudation).

4. Ankylosing Spondylitis (AS)
Ankylosing spondylitis (AS) is a progressive form of arthritis that affects <1% of the population. Joints between the spine and pelvis become inflamed, as do some of the ligaments, resulting in instability of the joints. Heredity factors play an important role in the development of AS. The disease is strongly associated with the presence of histocompatibility antigen HLA-B279. on the chromosomes of affected individuals. It begins in the sacroiliac joints and spreads up the spine.

5. Kaposi’s Sarcoma
Kaposi’s sarcoma (KS) KS an overgrowth of blood vessels that leads to malignant tumors and cancer of lymphatic tissue and skin commonly found in patients with AIDS. It is usually seen in cases of advanced AIDS.

6. Lymphoma
Functionless and damaged cells of the lymphatic system undergo overgrowth, decreasing the effectiveness of the lymphatic system. The lymphomas are caused by a disruption of cells during differentiation. Diagnosis is made on lymph node biopsy. There are two main types of lymphoma, characterized by painless lymph node swelling:
- Hodgkin’s Malignant lymphoma characterized by the presence of Reed-Sternberg cells. There are four stages of Hodgkin’s disease:
Stage I: Reed-Sternberg cells appear in one lymph node region.
Stage II: Reed-Sternberg cells appear in multiple lymph node regions on the same side of the diaphragm.
Stage III: Reed-Sternberg cells appear in multiple lymph node regions on both sides of the diaphragm.
Stage IV: Reed-Sternberg cells appear throughout the body.
- Non-Hodgkin’s (NHL) Cancers of the B lymphocytes that are characterized by the absence of Reed-Sternberg cells.

7. Rheumatoid Arthritis
Antibodies from the bloodstream move into the synovial lining of joints, causing joints to swell. The swelling affects the functionality of tendons, bones, and ligaments that move the joint, resulting in pain with movement.
Etiology is unknown, although genetics plays a part. The usual age of onset is 20. to 40. years, and it affects about 2% of the population. Inflammation and nodules around joints are common, usually involving the wrists, hands, knees, and feet.

8. Scleroderma
Antibodies attack connective tissues in an autoimmune response. This results in scar tissue (fibrosis) forming on skin, organs, gastrointestinal tract, blood vessels, and muscles, causing systemic sclerosis. It is a chronic disease of unknown etiology, usually seen in 30- to 50-year-old people.

9. Mononucleosis
Mononucleosis is a viral syndrome consisting of sore throat, enlarged lymph glands, and fevers. It is usually caused by the Epstein-Barr virus, but sometimes other viruses are the cause such as the cytomegalovirus. Occasionally, a rash may be seen. The spleen is sometimes enlarged because of sequestration of cells during the immune response.

10. Epstein-Barr Virus/Chronic Fatigue Syndrome (CFS)
Chronic fatigue syndrome is a chronic, multisymptom, multisystem syndrome in a previously healthy adult. It results from any of the five known viruses: Epstein-Barr, cytomegalovirus, coxsackievirus B, adenovirus type I, and human herpes virus 6. In an unknown way, the viruses disturb the immune system, which is then unable to adequately fight off the virus.

11. Lyme Disease
A bite from a deer tick causes the bacteria (a spirochete) Borrelia burgdorferi, to be transmitted into the human bloodstream. The patient presents with fever, myalgias, and the classic bull’s-eye rash, erythema chronicum migrans, up to 3. weeks following the bite.

12. Septic Shock
Septic shock starts with bacteremia, usually gram-negative bacteria infecting the blood. The sources are usually the genitourinary system, gastrointestinal tract, and lungs. The infection may be underlying for some time before shock develops. Once the cascade from bacteremia to septic shock starts, it may be difficult to halt the process. Shock may occur more quickly in patients who are elderly, immunocompromised, or with other comorbidities. In response to a bacteria infection, TNF-alpha, and other inflammatory chemicals are released into the blood, causing an increase in the blood leaking from vessels into both the infected and uninfected tissues (vascular permeability).

13. Systemic Lupus Erythematosus (SLE)
Systemic lupus erythematosus (SLE) is a chronic inflammatory immune disorder affecting the skin and other body organs. Antibodies to DNA and RNA cause an autoimmune inflammatory response, resulting in swelling and pain. It is most common in young women, and has both a strong genetic and gender factor. The etiology is not known.

14. Immunologic Blood Studies
The antinuclear antibodies (ANA) test is a screening test for the detection of antibodies to nuclear antigens. Close to 100% of patients with SLE show positive evidence.
- ESR: The erythrocyte sedimentation rate is useful in differentiating between inflammatory and neoplastic disease. Serial values are helpful to track disease severity.
- SS-A and SS-B: SS-A antibodies can be detected in about 30% of SLE patients. SS-B antibodies have a high specificity for the sicca complex, caused by diminished secretion from glands.
- Rheumatoid Factor: Rheumatoid factor is an IgM antibody that is associated with rheumatoid arthritis. Blood is drawn from a vein and a study is conducted to determine if the blood contains this immunoglobulin antibody. Fifty percent of patients with rheumatoid arthritis have this antibody.
- Scleroderma Autoantibodies: The scleroderma antibody is found in venous blood of patients who have scleroderma. The autoantibodies are positive in about 25. to 40% of scleroderma patients.

15. Lymphangiography
This test produces a radiographic image of the lymphatic system to determine if there are any abnormalities such as edema of the legs, Hodgkin’s and non-Hodgkin’s lymphoma, lymphadenopathy, and lymphatic metastases. The results are useful in the staging of lymphoma and Hodgkin’s lymphoma and to determine the efficacy of treatment.

Basic Questions
Immune System

1. What are B cells?
B cells provide a humoral immune response, because they produce an antigen-specific antibody.

2. What are T cells?
T cells provide a cellular immune response.

3. What are CD8. cells?
CD8. cells are responsible for destroying foreign and viral inhabited cells, and suppressing immunologic functions.

4. What are CD4. cells?
CD4. cells, also known as T-helper cells, stimulate immune functions, such as B cells and macrophages.

5. What is a macrophage?
A macrophage is a cell whose functions include ingesting foreign or invading cells.

6. What is acquired immunodeficiency syndrome (AIDS)?
AIDS is a disease caused when the human immunodeficiency virus (HIV) enters a cell, and HIV replicates, causing the cell to reproduce more infected cells. It also frequently causes cell death.

7. What is a major result of the human immunodeficiency virus (HIV)?
HIV causes malfunction of T cells, which protect the body from invading microorganisms. The CD4. lymphocyte is most often affected, followed by B lymphocytes and macrophages. Immunodeficiency results.

8. What is anaphylaxis?
An allergen, usually food or medication, enters the body, causing the release of histamines, which result in capillaries dilating and smooth muscle contracting. This results in edema, respiratory distress, hypotension, and skin changes, leading to an allergic reaction. Lesser degrees of extreme allergy are urticaria (hives) and angioedema (swelling caused by exudation).

9. What is ankylosing spondylitis (AS)?
AS is a progressive form of arthritis that affects <1% of the population. Joints between the spine and pelvis become inflamed, as do some of the ligaments, resulting in instability of the joints.

10. What is a Kaposi’s sarcoma (KS)?
KS is an overgrowth of blood vessels that leads to malignant tumors and cancer of lymphatic tissue and skin commonly found in patients with AIDS. It is usually seen in cases of advanced AIDS.

11. What is lymphoma?
Functionless and damaged cells of the lymphatic system undergo overgrowth, decreasing the effectiveness of the lymphatic system.

12. What is a common sign of lymphoma?
Painless lymph node swelling is a common sign of lymphoma.

13. What are the two main types of lymphoma?
Two main types of lymphoma are Hodgkin’s and non-Hodgkin’s lymphoma.

14. What is Hodgkin’s lymphoma?
Hodgkin’s lymphoma is malignant lymphoma characterized by the presence of Reed-Sternberg cells.

15. What is non-Hodgkin’s lymphoma (NHL)?
NHL is cancer of the B lymphocytes and is characterized by the absence of Reed-Sternberg cells.

16. What is rheumatoid arthritis?
Antibodies from the bloodstream move into the synovial lining of joints, causing joints to swell. The swelling affects the functionality of tendons, bones, and ligaments that move the joint, resulting in pain with movement.

17. What is scleroderma?
Antibodies attack connective tissues in an autoimmune response. This results in scar tissue (fibrosis) forming on skin, organs, gastrointestinal tract, blood vessels, and muscles, causing systemic sclerosis.

18. What is mononucleosis?
Mononucleosis is a viral syndrome consisting of sore throat, enlarged lymph glands, and fevers.

19. What is chronic fatigue syndrome (CFS)?
CFS is a chronic, multisymptom, multisystem syndrome in a previously healthy adult. It results from any of the five known viruses: Epstein-Barr, cytomegalovirus, coxsackievirus B, adenovirus type I, and human herpes virus 6. In an unknown way, the viruses disturb the immune system, which is then unable to adequately fight off the virus.

20. What is Lyme disease?
A bite from a deer tick causes the bacteria (a spirochete) Borrelia burgdorferi, to be transmitted into the human bloodstream. This is referred to as Lyme disease. The patient presents with fever, myalgias and the classic bull’s-eye rash, erythema chronicum migrans up to 3. weeks following the bite.

21. What is septic shock?
Septic shock starts with bacteremia, usually gram-negative bacteria infecting the blood. The sources are usually the genitourinary system, gastrointestinal tract, and lungs. The infection may be underlying for some time before shock develops. Once the cascade from bacteremia to septic shock starts, it may be difficult to halt the process.

22. What is systemic lupus erythematosus (SLE)?
SLE is a chronic inflammatory immune disorder affecting the skin and other body organs. Antibodies to DNA and RNA cause an autoimmune inflammatory response, resulting in swelling and pain.

23. What is the usefulness of knowing the erythrocyte sedimentation rate (ESR)?
The ESR is useful in differentiating between inflammatory and neoplastic disease.

24. What is the rheumatoid factor?
The rheumatoid factor is an IgM antibody that is associated with rheumatoid arthritis. Fifty percent of the patients with rheumatoid arthritis have this antibody.

25. What is lymphangiography?
This test produces a radiographic image of the lymphatic system to determine if there are any abnormalities, such as edema of the legs, Hodgkin’s lymphoma, non-Hodgking lymphoma, lymphadenopathy, and lymphatic metastases.