Diseases of the Immune System – Chapter 6

Question 1

What are the 4 major types of immunologic disorders?

Answer 1

1) hypersensitivity reactions
2) autoimmune diseases
3) immunologic deficiency syndromes 4) amyloidosis (p. 200)

Question 2

Hypersensitivity reactions can be initiated by ______.

Answer 2

Exogenous and endogenous antigens, particular susceptibility genes and an imbalance between the effector mechanisms of immune responses and the control mechanisms that serve to normally limit such response. (p. 200)

Question 3

List the four types of hypersensitivity reactions and give some examples of each.

Answer 3

Type I hypersensitivity - immediate
Anaphylaxis, atopic bronchial asthma

Type II hypersensitivity - antibody-mediated,
Autoimmune hemolytic anemia, Goodpasture Syndrome

Type III hypersensitivity - immune complex mediated
Arthus reaction, serum sickness, systemic lupus erythematosus

Type IV hypersensitivity - cell-mediated
Tuberculosis, contact dermatitis, multiple sclerosis (p. 201)

Question 4

Define immediate hypersensitivity and identify which antibodies control this reaction.

Answer 4

Type I (immediate) hypersensitivity is defined as a rapidly developing immunologic reaction occurring within minutes after the combination of an antigen with antibody bound to mast cells in individuals previously sensitized to the antigen. In humans, type I reactions are mediated by IgE antibody-dependent activation of mast cells and other leukocytes. (p. 201)

Question 5

List the preformed and lipid mediators of immediate hypersensitivity reactions.

Answer 5

Preformed Mediators- Vasoactive amines, Enzymes, Proteoglycans
Lipid Mediators- Leukotrienes, Prostaglandin D2, Platelet activating factor, Cytokines (p. 203)

Question 6

List some common inciting agents to systemic anaphylaxis and give some of the common clinical symptoms of this reaction.

Answer 6

Inciting agents - Heterologous proteins, hormones, enzymes, polysaccharides, and drugs, food allergens, insect toxins
Symptoms – itching, hives, laryngeal edema, vomiting, abdominal cramps, diarrhea, shock. (p. 205)

Question 7

Define atopy; list some possible inciting agents and the most common clinical symptoms.

Answer 7

The term atopy implies a predisposition to develop localized immediate hypersensitivity reactions to inhaled or ingested allergens.
Inciting agents – pollen, animal dander, house dust, fish
Symptoms – urticaria, angioedema, allergic rhinitis, some forms of asthma. (p. 204)

Question 8

Define immune complex-mediated hypersensitivity reaction.

Answer 8

Immune complex-mediated hypersensitivity reaction is induced by antigen-antibody complexes that produce tissue damage as a result of their capacity to activate the complement system eliciting inflammation at the sites of deposition. (p. 207)

Question 9

Describe the pathogenesis of systemic immune complex disease and give some clinical and pathologic presentations. (3 phases)

Answer 9

1) Formation of immune complexes in the circulation
2) Deposition of the immune complexes in various tissues, thus initiating
3) An inflammatory reaction in dispersed sites throughout the body.
Clinical presentation: fever, urticaria, arthralgias, lymph node enlargement, and proteinuria. Pathologic presentation: necrotizing vasculitis with necrosis of the vessel wall and intense neutrophilic infiltration (p. 207-208)

Question 10

Define an Arthus reaction and its characteristic pathologic changes.

Answer 10

The Arthus reaction is defined as a localized area of tissue necrosis resulting from acute immune complex vasculitis. Fibrinoid necrosis of the vessels is seen on light microscopy. (p. 208)

Question 11

Define T cell-mediated hypersensitivity reactions and give some common examples.

Answer 11

The T cell-mediated type of hypersensitivity is initiated by antigen-activated T lymphocytes. It includes the classic delayed type hypersensitivity reactions initiated by CD4+ T cells and direct cell cytotoxicity mediated by CD8+ T cells.
Examples – tuberculosis mechanisms, contact dermatitis, inflammatory bowel disease. (p. 209)

Question 12

List the two major types of cell mediated hypersensitivity.

Answer 12

1) Delayed-type hypersensitivity
2) T-cell mediated cytotoxicity (p. 211)

Question 13

What are the histologic classifications of glomerular changes in systemic lupus erythematosus?

Answer 13

Minimal mesangial lupus nephritis, mesangial proliferative lupus nephritis, focal lupus nephritis, diffuse lupus nephritis, membranous lupus nephritis, and advanced sclerosing lupus nephritis.
(p. 223-224)

Question 14

What are the two mechanisms involved in transplant rejection?

Answer 14

1) T-cell mediated reactions
2) Antibody-mediated reactions (p. 233)

Question 15

list the 5 various types of renal transplant rejection reactions

Answer 15

Hyperacute rejection
Acute rejection
Acute Cellular rejection
Acute Humoral (Rejection Vasculitis)
Chronic Rejection

Question 16

Hyperacute rejection:

Answer 16

This form of rejection occurs within minutes or hours after transplantation. Glomeruli undergo thrombotic occlusion of the capillaries and fibrinoid necrosis occurs in the arterial walls.

Question 17

Acute rejection:

Answer 17

This may occur within days of transplantation in the untreated recipient or may appear suddenly months or even years later, after immunosuppression has been used and terminated; combined cellular and humoral rejection.

Question 18

Acute Cellular rejection:

Answer 18

is most commonly seen within the initial months after transplantation and is heralded by an elevation of serum creatinine level followed by
clinical signs and biochemical signs and endothelitis

Question 19

Acute Humoral (Rejection Vasculitis):

Answer 19

is mediated by antidonor antibodies, and hence it is manifested primarily by damage to the blood vessels; necrotizing vasculitis.

Question 20

Chronic Rejection:

Answer 20

present clinically with a progressive rise in serum creatinine level over a period of 4-6 months; dominated by vascular changes, interstitial fibrosis, tubular atrophy, and loss of renal parenchyma. (p. 233-234)

Question 21

Describe the mechanism behind graft vs. host disease.

Answer 21

Graft vs. host disease occurs in any situation in which immunologically competent cells or their precursors are transplanted into immunologically crippled recipients, and the transferred cells recognize alloantigens in the host. (p. 236)

Question 22

Describe the mechanism behind graft vs. host disease.

Answer 22

Graft vs. host disease occurs in any situation in which immunologically competent cells or their precursors are transplanted into immunologically crippled recipients, and the transferred cells recognize alloantigens in the host. (p. 236)

Question 23

Define Systemic Lupus Erythematosus (SLE).

Answer 23

SLE is the prototype of the multisystem disease of autoimmune origin, characterized by a vast array of autoantibodies, particularly antinuclear antibodies.
Acute or insidious in its onset, it is a chronic remitting and relapsing, often febrile illness characterized principally by injury to the skin, joints, kidney, and serosal membranes.

Question 24

Define Sjögrens syndrome.

Answer 24

Sjögrens syndrome is a chronic disease characterized by dry eyes (keratoconjunctivitis sicca) and dry mouth (xerostomia) resulting from immunologically mediated destruction of the lacrimal and salivary glands. (p. 226)

Question 25

Define Systemic Sclerosis (scleroderma). it us characterized by what 3 things:

Answer 25

Systemic sclerosis (scleroderma) is a chronic disease characterized by:
1. Chronic inflammation thought to be the result of autoimmunity
2. Widespread damage to small blood vessels
3. Progressive interstitial and perivascular fibrosis in the skin and multiple organs. (p. 228)

Question 26

Define inflammatory myopathy and give three examples.

Answer 26

Inflammatory myopathies comprise an uncommon, heterogeneous group of disorders characterized by immunologically mediated injury and inflammation of mainly the skeletal muscles.

3 examples: Dermatomyositis, Polymyositis, Inclusion-body myositis. (p. 231)

Question 27

Define polyarteritis nodosa.

Answer 27

Polyarteritis nodosa belongs to a group of diseases characterized by necrotizing inflammation of the walls of blood vessels and showing strong evidence of an immunologic pathogenetic mechanism. (p. 231)

Question 28

DiGeorge syndrome

Answer 28

is a T-cell deficiency that results from failure of development of the 3rd and 4th pharyngeal pouches leading to thymic hypoplasia.

Question 29

Wiskott-Aldrich Syndrome

Answer 29

is an X-linked recessive disease characterized by thrombocytopenia, eczema, and a marked vulnerability to recurrent infection, ending in early death.

Question 30

Acquired immunodeficiency syndrome

Answer 30

is caused by the retrovirus, human immunodeficiency virus and characterized by profound immunosuppression that leads to opportunistic infections, secondary neoplasms, and neurologic manifestations. (p. 241-243)

Question 31

The most common fungal infection of patients with AIDS is_______.

Answer 31

Pneumocystosis (pneumocystis jirovei) (p. 253)

Question 32

Define amyloidosis and amyloid.

Answer 32

Amyloidosis is group of diseases having in common the deposition of similar appearing proteins.

Amyloid is a pathologic proteinaceous substance, deposited in the extracellular space in various tissues and organs of the body in a wide variety of clinical settings. (p. 256)

Question 33

Where are amyloid deposits found in the kidney? What are the special stains for amyloid and what do the characteristic positive stains look like?

Answer 33

Glomeruli, blood vessel walls, and interstitium Congo Red
Apple-green birefringence (p. 257, 261)