Learning Exercise - Immunology

Question 1

Define immune response.

Answer 1

The overall actions and interactions of the immune system to provide immunity through a sequence of related host defense events beginning when a host encounters a substance as being “foreign” or “non-self” and leading to cellular and chemical defensive actions.

Question 2

What are the general characteristics of erythrocytes and leukocytes / monocytes?

(include concentration within the body / percentage of type of leukocyte / what it responds to)

Answer 2

Erythrocytes are red blood cells (minimally covered) 4-6 million per microliter

Leukocytes are white blood cells: 4,500 - 11,000 per microliter

Types of leukocytes:

(1) Basophils: (0.5-1%): inflammatory process
(2) Eosinophils: (1-5%): allergic responses
(3) Neutrophils (~45-75%): inflammation response
(a) The primary phagocytic cells
(b) Mature at the rate of about 10^10 per day
(c) Circulate about 6-10 hours, then adhere to endothelium of blood vessels and wait to respond to inflammation; short-lived (few days)

Monocyte: (2-8%): inflammation response: Moderately phagocytic; matures into macrophages & dendritic cells

Question 3

What are the general functions of lymph nodes and the spleen?

Answer 3

Lymph Nodes and Spleen
Pieces of the antigen are processed through the lymph nodes and/or spleen in a “percolating / meandering” manner where antigens come in contact with cells of the immune system, and those cells become activated to go into action (predetermined type of action).

(1) Lymph nodes (local/regional): Lymphatic fluid containing antigens and APCs flow through and antigens encounter and activate precommitted lymphocytes; responds to local or regional infections
(2) Spleen (systemic): Blood-borne antigens and APCs meander through the spleen cells where they encounter and activate precommitted lymphocytes; responds to systemic infections

• *L**ymph = local
• *S**pleen = systemic

Question 4

What are the major characteristics of MHC proteins?

Answer 4

1. ) located on the surface of tissue and blood cells which identify cells belonging to a specific individual.
2. ) Allow the body to recognize Self vs. Non-self
3. ) Classes:
4. Class I – (one amino acid chain) found on virtually every cell in the body
5. Class II – (two amino acid chains) found only on certain cells of the immune system, particularly dendritic cells, macrophages, and B-cells
6. MHC molecules present antigens which are recognized by T-cells
7. Blood and tissue of another person is sensed as being “non-self” (except for identical twins), and thus an immune response occurs

Question 5

What are the major characteristics of dendritic cells?

Answer 5

Specialized cells located in tissues exposed to the external environment that participate in initiating antigen recognition and immune response. (phagocytic)

(e.g. lymphoid tissue; epithelia of skin, gastrointestinal, and respiratory tracts, and certain other tissues)