Mast and Basal Cells 1

Question 1

Where do mast cells and basal cells usually hang out?

Answer 1

Pulmonary and GI mucosa

Question 2

Band or stab cells are immediate precursors to what 3 cells?

Answer 2

Neutrophils

Basophils

Eosinophils

Question 3

What are basophils and mast cells primary functions?

Answer 3

They battle helminths, bacteria and snake venom

Question 4

Substances in granules of eosinophils, basophils and mast cells will cause what general results?

Answer 4

Vasodilatation (and increased permeability)

Smooth muscle contraction (bronchial most important)

Question 5

What do the granules in eosinophils, basophils and mast cells contain?

Answer 5

Histamine

Heparin

Peroxidase (important in ROS)

Tryptase (tissue breakdown)

Hydrolases (digestive enzymes)

Question 6

Why is an allergen not an antigen?

Answer 6

An allergen only causes a hyperallergic reaction in 20% of the population. To be an antigen it would have to have that effect on 100% of the population

Question 7

Why do 20% of people have an allergic reaction to a particular substance?

Answer 7

They have a genetic predisposition

Question 8

What part of the immune system is overproduced in people with allergic reactions?

Answer 8

Th2 Cells

Question 9

TH2 cells produce which interleukins?

Answer 9

IL-4 and IL-5 which act on B cells

Question 10

How is IL-4 involved in allergic reactions? What effect does it have on B cells?

Answer 10

It encourages the formation of IgE

• Called class switching

Question 11

What effect does IL-5 have on B cells?

Answer 11

It causes class switching to IgA

Question 12

In an allergic reactions, what substances are released from a vesicle (from a mast cell)?

What do they do?

Answer 12

• Histamine
• Tryptases
• Hydroxylases
• Peroxidases

Histamines attach to endothelial cells which causes a contraction of the cells which causes the fluids to leak

The other substances act on smooth muscles which causes bronchoconstriction and esophagea

Question 13

In an allergic reaction (involving mast cells) what happens when cyclic GMP increases vs cyclic AMP increasing

Answer 13

• When cyclic GMP increases
  
  • Allergic reaction proceeds
• When cyclic AMP increases
  
  • Allergic reaction is blocked

Question 14

What medicine is given in an allergic reaction to increase cAMP and thereby stop the reaction?

Answer 14

Epinephrine

Question 15

What can happen when IgE (the Fc portion) immunoglobulin binds to the receptor on the mast cell?

Answer 15

It can trigger an allergic reaction. There have to be 2 IgEs with bound allergins side by side to create a cross-link which then triggers the increase in cGMP which triggers the rest of the cascade

Question 16

What are the chemotactic factors (that are released along with histamine, etc. from the basophil and mast cell) for eosinophils called?

Answer 16

Eotaxins and leukotriene B4

Question 17

In an allergic reaction, after the initial degranulation (mast cells and basophils) what is produced and when?

Answer 17

Lipid metabolites (or mediators) from arachidonic acid produced from 2 to 6 hours

• Called Slow Reacting Substance of Anaphylaxis (SRS-A)

Question 18

What lipid metabolites (or mediators) from arachidonic acid are produced?

Answer 18

Leukotrienes B4, C4 and D4

Prostaglandins

Together they are called the slow reacting substances of anaphylaxis (SRS-A)

Question 19

What does Leukotriene B4 do in an allergic reaction? What 2 things is it trying to do (along with eotaxin)?

Answer 19

• It is a chemotactic factor to attract basophils, neutrophils and eosinophils
• It is trying to amplify the allergic reaction and it is trying to contain that activity locally by attracting auditors (eosinophils) to make sure that this is not an overreaction

Question 20

Why to Leukotriene B4 and eotaxin call basophils and neutrophils?

Answer 20

To start inflammation

Question 21

What actions do Leukotriene C4 and D4 and prostaglandin have?

Answer 21

• Vasodilation
• Increased vascular permeability
• Smooth muscle contraction
• LC4 and LD4 are thousands of times more potent than histamine

Question 22

What is an anaphylactoid like reaction?

Answer 22

• It is a reaction where a bacteria or allergen attaches to a TLR (a pattern recognition receptor) which works with CD14 on the surface of the mast cell and basophil which leads to a typical allergic reaction
• IgE with cross links of the allergin is not needed

Question 23

When eosinophils (along with neutrophils and basophils) are called to the allergic reaction by the mast cells, what do they do?

Answer 23

They secrete

• histaminases (breaks down histamine) and
• Arylsufatases (reduces SRS-A)

to contain the reaction

Question 24

What 2 medical conditions will cause eosinophils (eosinophilia) to increase?

Answer 24

• Asthmatics
• Parasitic infections (Helminths or Nematodes)

Question 25

When eosinophils degranulate, what 2 substances are released that will ultimately cause tissue damage?

Answer 25

Peroxidases and leukotienes

Question 26

What antibody takes part in ADCC (Antibody Dependent Cellular Cytotoxicity)?

Answer 26

IgE ADCC is probably the major function of eosinophils

Question 27

What immune cells make IgE that then take part in ADCC?

Answer 27

B Cells

Question 28

Eosinophils surface receptors for what 2 antibodies?

Answer 28

IgG and IgE

Question 29

A nematode is destroyed by ADCC (Antibody Dependent Cellular Cytotoxicity). What protein does an eosinophil release from its granules that attack the worm?

Answer 29

Major Basic Protein

Question 30

What part of a CBC is used to gauge the intensity of asthma?

Answer 30

Eosinophil count

Question 31

What is the hypothesis for the cause of asthma?

Answer 31

It is caused by the allergic reactions mediated by mast cells and basophils

Question 32

What does major basic protein (from eosinophils) do to the pulmonary epithelium in asthmatics?

Answer 32

It damages it