Disorders of the Immune System

Question 1

What is a type 1 hypersensitivity reaction?

Answer 1

It is an immediate hypersensitivity response to an environmental allergen. Allergy is the term used by healthcare providers to denote a type 1 hypersensitivity.

Question 2

What is the pathogenesis behind a type 1 hypersensitivity reaction?

Answer 2

The pathogenesis begins with the antibody IgE. Upon initial exposure to the allergen, IgE binds with the allergen. This primes the stages for a reaction to occur later. Upon re-exposure, the allergen antigen binds with the previously formed antigen- IgE complex. The mast cell detects this complex and begins to rupture. It releases histamine and triggers the inflammatory cascade.

Question 3

What are the clinical manifestations of an allergic reaction?

Answer 3

1. rhinitis (inflammation of membranes that line the nose)
2. conjunctivitis (inflammation of membranes that line the eyes)
3. Asthma (bronchoconstriction)
4. Angioedema

Question 4

What is the treatment for type 1 hypersensitivity reaction?

Answer 4

Epinephrine is the treatment because it dilates bronchial smooth muscle

Question 5

What is autoimmunity?

Answer 5

Genetically predisposed, and results in an individual’s host system attacking its own cells. More common in women.

Question 6

What is alloimmunity?

Answer 6

Occurs when an individual immune system attacks another member of the same species’ antigens/tissues.
Ex: ABO and Rh incompatibility between mother and fetus, and transplant rejection

Question 7

What is systemic lupus?

Answer 7

Chronic, multisystem, inflammatory disease that primarily affects women aged 20-40.

Question 8

What are the clinical signs of lupus?

Answer 8

1. butterfly rash that is localized to cheeks
2. photosensitivity
3. arthritis of two or more peripheral joints
4. inflammation of the pericardial or pleural sacs
5. pulmonary hemorrhage
6. anemia, leukopenia, thrombocytopenia

Question 9

What is the pathogenesis of lupus?

Answer 9

Antibodies form against DNA, RNA, platelets, nucleic acids, erythrocytes, phospholipids, lymphocytes, and other components of the cellular nucleus. These antibody-antigen complexes are deposited in a variety of tissues in the organs which causes an inflammatory response that ultimately causes tissue damage.

Question 10

What is rheumatoid arthritis?

Answer 10

Systemic autoimmune disease that causes chronic inflammation of connective tissues primarily in the joints. The HLA-DRB1 gene is associated with an increased risk of developing RA.

Question 11

What are the clinical signs of rheumatoid arthritis?

Answer 11

1. widespread symmetrical joint swelling
2. erythematic joints that are warm to touch
3. loss of function in joints
4. Weight loss, weakness, and anorexia
5. Extraynovial rheumatoid nodules can be invasive and may involve cardiac valves, pericardium pleura, the lungs, and spleen.

Question 12

What is the pathogenesis of rheumatoid arthritis?

Answer 12

In this disorder, IgM autoantibodies are formed against IgG antibodies and they form together to make an antigen-antibody complex. These complexes are deposited into the synovial membranes which then start the inflammatory process. This causes tissue damage which results in joint inflammation and destruction of synovial membranes.