Chapter 13 Learning Objectives

Question 1

How does the third line of defense is different from the other two.

Answer 1

Third line is adaptive and involves B and T cells. Acquired after immunization and exposure to infection. B and T cells only react to one specific antigen or immunogen.

Question 2

Four stages of a specific immune response.

Answer 2

1. Lymphocyte development and clonal deletion
2. Presentation of antigen and clonal selection
3. Challenge of B and T cells by antigens (immunogens)
4. • T-cell response: CELL MEDIATED IMMUNITY

• B-cell response: Production and activities of anitbodies. B cells become plasma cells. Humoral immunity.

Question 3

Roll of cell marker in immune response

Answer 3

Major role is to “accept” or “grasp” antigens in some form

Question 4

2 major histocompatibility structures

Answer 4

MHC I:
- Found on all NUCLEATED cells (except RBC). Helps the immune system recognize infected or abnormal cells (like virus-infected or cancerous cells). It presents tiny pieces of proteins from inside the cell to killer T-cells (CD8+). If the protein looks harmful, the immune system attacks the cell.

MHC II:
- Found on APCs (macrophages, B cells, dendritic cells). It presents pieces of proteins from outside the cell (such as bacteria) to helper T-cells (CD4+), which then activate other parts of the immune system to fight the infection.

Question 5

Place of Maturation of T-cells

Answer 5

Matures in Thymus; created in Red Bone Marrow

Question 6

Place of Maturation of B-cells

Answer 6

Created and matures in Red Bone Marrow

Question 7

Characteristics of antigens that optimize their immunogenicity

Answer 7

Shape or type of molecule - usually a protein or having some peptide sequence

Size - 10,000 Da (or amu) or greater

Foreign - microbes, plant molecules, foreign human molecules (ie. different blood types or cells with the wrong MHC-I molecule), or animal cells are considered foreign

Accessibility - processed and presented antigens are more immunogenic than non-processed and presented antigens. Your immune system is alerting the lymphocytes about antigens.

Question 8

Types of cells that act as antigen-presenting cells (APC)

Answer 8

Dendritic cells
Macrophages
B-cells

Question 9

Main difference between T helper cells and T cytotoxic cells

Answer 9

• Helper T cells have CD4 coreceptors: help the T-cell receptor bind to MHC class II molecules
• Cytotoxic T cells have CD8 coreceptors:
  help the t-cell bind to MHC class I molecules

Question 10

Five types of antibodies and important facts about each

Answer 10

IgG: Monomer
- Fc binds to Phagocytes. Most abundant in total antibody serum. Able to cross over to offspring.

IgA: Monomer and Dimer
- Dimer is a secretary antibody on mucous membranes; monomer is in small quantities in blood

IgM: Pentamer
- Produced at first response to antigen. Can serve as a B-cell receptor.

IgD: Monomer
- The receptor on B cells and a triggering molecule for B-cell activation.

IgE: Monomer
- Fc binds to mast cells and basophils. Antibody of allergy and worm infections. Also mediated Anaphylaxis, asthma, etc.

Question 11

IL-2

Answer 11

Secretes and activates cytotoxic T-cells. Activate immunity.

Question 12

IL-4 & IL-5

Answer 12

Activate B-cells (plasma cells). Help create antibodies. Secreted by T-helper cells.