Chapter 16 Terms (Autoimmunity)

Question 1

Autoimmunity

Answer 1

The failure of mechanisms of the immune system to inactivate or eliminate self-reactive cells.

Question 2

Self-Tolerance

Answer 2

Results from the delibrate inactivation or destruction of lymphocytes bearing BCRs or TCRs that recognize & bind self-epitopes.

Question 3

Central Tolerance

Answer 3

• Occurs during early differentiation of B cells in the bone marrow & t ceclls in the thymus.
• Mechanism by which newly developing T & B cells are rendered non-reactive to self.

Question 4

Peripheral Tolerance

Answer 4

• Several mechanisms that control or eliminate autoreactive B & T cells after they exit the bone marrow or thymus.
• Includes Anergy & Suppression

Question 5

Anergy

Answer 5

• A state of nonresponsiveness in lymphocytes after their receptors bind antigen (B cell) or pMHC (Tcell).
• Receipt of the first signal in the absence of second signal causes naÏve T cells to enter anergy.
• CD8⁺ & B Cells

Question 6

Suppression

Answer 6

• Regulatory cells (Usually T cells) inhibit the activity of other cells.
• CD4⁺CD25⁺ T cells diminish activity of T cells stimultaed by various epitopes

Question 7

T_h1 Cells

Answer 7

• The host immunity effector against intracellular bacteria & protozoa.
• Triggered by IL-12 & IL-2
• Effector cytokine is IFN-gamma
• Main effector cells are mcrophages, CD8 T cells, IgG B cells, & IFM-gamma CD4 T cells

Question 8

T_h2 Cells

Answer 8

• Host immunity effectors against extracellular parasites including helminths
• Triggered by IL-4
• Their effector cytokines are IL-4, IL-5, IL-9, IL-10, & IL-13
• Main effector cells are eosinophils, basophils, mast cells, B cells, & IL-4/IL-5 CD4 T cells

Question 9

Autoimmune Inflammatory Bowel Disease

Answer 9

• May be due to changes that favor developement of T_h1-like cell-mediated inflammatory responses, perhaps triggered by pathogenic bacteria.
• Includes: Crohn’s Disease & Ulcerative Colitis

Question 10

Molecular Mimicry

Answer 10

A process in which infection by particular microbes is associated with the subsequent development of specific autoimmune diseases.

Question 11

Reactive Arthritis

Answer 11

• A group of inflammatory arthritis diseases that occur more frequently in individuals who have had food poisoning.
• Includes Ankylosing Spondylitis & Reiter Disease

Question 12

Ankylosing Spondylitis

Answer 12

• Usually involving the lower spine
• Chronic inflammatory disease of the axial skeleton.

Question 13

Reiter Disease

Answer 13

Affecting the joints of the lower limbs & the gastrointestinal/genital/urinary tracts.

Question 14

Myasthenia gravis

Answer 14

• Neuromuscular disease that leads to fluctuating muscle weakness & fatigue.
• In most common cases, muscular weakness is caused by circulating antibodies that block acetylcholine receptors.
• Localized

Question 15

Epitope Spreading (ES)

Answer 15

Development of an immune response to epitopes distinct from, & noncrossreaction with, the disease-causing epitope.

Question 16

Immunologically Privileged Sites

Answer 16

Sites in the body that are associated with some degree of isolatio from the immune system

Question 17

Blood-Brain Barrier

Answer 17

Consists of dense, tightly packed vascular endothelium that limits the flow of cells & large molecules from the vasculature into the brain, thus decreasing the ability of the immune system to infiltrate the brain.

Question 18

Cryptic Epitope

Answer 18

If the molecule is altered by denaturation or cleavage, the “hidden” internal epitopes may become exposed & available for recognition & binding by antibodies.

Question 19

Rheumatoid Factors

Answer 19

IgM antibodies directed at the cryptic carbohydrate structures on antigen-bound IgG molecules.

Question 20

Neoantigens

Answer 20

Self-antigens that have been modified by some extrinsic factor so that they appear foreign to the immune system.

Question 21

Cell-Mediated Autoimmune Diseases

Answer 21

1. Insulin-Dependent Diabetes Mellitus (type 1)
2. Multiple Sclerosis
3. Reactive Arthritis
4. Rheumatoid Arthritis

Question 22

HLA Association with Autoimmune Disease

Answer 22

The risks for many autoimmune diseases appear to be associated with the presence of particular HLA genes.

Question 23

Relative Risk

Answer 23

Compares frequency of particular disease among carriers of a particular HLA gene witht he frequency among non-carriers.