Cells & Tissue of Immune System

Question 1

What is the normal cell count for RBCs?

Answer 1

5.0 x 10^6

Question 2

What is the normal cell count for platelets ?

Answer 2

2.5 x 10^5

Question 3

What is the normal cell count for Leukocytes ?

Answer 3

7.3 x 10^3

Question 4

Describe Phagocytes

Answer 4

• mononuclear monocytes/macrophages
• dendritic cell
• polymorphonuclear granulocytes = neutrophils, eosinophils, basophils

Question 5

What are some examples of macrophages ?

Answer 5

• alveolar macrophages - lung
• histiocytes - connective tissue
• mesangial cells - kidney
• microglial cells - CNS

Question 6

How are macrophages differentiated ?

Answer 6

stem cells -> mono blast -> monocyte -> macrophage

Question 7

Where can you find monocytes ?

Answer 7

• they circulate in the blood and migrate to tissues where they differentiate into macrophages

Question 8

Describe Receptor Expression

Answer 8

• macrophage expresses receptors for many bacterial constituents
• bacteria binding to macrophage receptors intimate the release of cytokines & small lipid mediators of inflammation
• macrophages engulf & digest bacteria to which they bind

Question 9

What are some bactericidal products from phagocytes ?

Answer 9

• acidification,
• toxic nitrogen oxides,
• antimicrobial peptides

Question 10

How to released cytokines mediate further inflammatory responses?

Answer 10

• vasodilation & increased vascular permeability cause redness, heat &swelling
• inflammatory cells migrate into tissue, releasing inflammatory mediators that cause pain

Question 11

What are some examples Dendritic cells

Answer 11

• Langerhans cells
• interstitial dendritic cells
• circulating dendritic cells

Question 12

Describe Neutrophils

Answer 12

• polymorphonuclear cell
• 95% of circulating granulocytes
• 1st cell to arrive at the site of inflammation
• phagocytose bacteria
• circulate in blood for 7-10 hours before migrating to tissues

Question 13

Describe Eosinophils

Answer 13

• 2-5% circulating leukocytes
• granules stain with basic eosin red
• role in removal of parasitic organisms & asthma pathology

Question 14

Describe Basophils

Answer 14

• 0.2% of circulating leukocytes
• granules stain with acid dye methylene blue
• granules contain heparin & histamine
• plays a role in allergic response

Question 15

Describe mast cells

Answer 15

• resides near small blood vessels
• upon activation they release histamine & other pharmacologically active substances from their granules
• play major role in allergic disease development

Question 16

Describe natural killer cells

Answer 16

• 5-10% of blood lymphocytes
• do not express T or B cell receptors
• recognise & destroy virus-infected cells and certain tumour cells
• detection via - lack of MHC I & Fc receptors

Question 17

Describe Gamma/Delta T cells

Answer 17

• intraepithelial cells
• part of the innate & adaptive immune system
• limited diversity

Question 18

Describe B lymphocytes

Answer 18

• each B cell is genetically programmed to produce an antibody of unique specificity
• B cell receptor binding of antigen results in B cell differentiation into plasma cell

Question 19

What are the stages of maturation for plasma cells ?

Answer 19

1. stem cell
2. pre-B cell
3. immature B cell
4. mature B cell
5. activated B cell
6. Antibody-secreting cell

Question 20

Describe T lymphocytes

Answer 20

• 2 types = T Helper cells & Cytotoxic T lymphocytes

Question 21

Describe T Helper cells

Answer 21

• express cytokines to coordinate the immune response
• express T cell receptor (TCR) and CD4 co-receptor
• Th1 & Th2

Question 22

Describe Cytotoxic T Lymphocytes

Answer 22

• express T cell receptor & CD8 co-receptor
• destroy infected cells directly

Question 23

Where are B lymphocytes matured ?

Answer 23

in the bone marrow

Question 24

Where are T lymphocytes matured ?

Answer 24

thymus