L 26 Antihistamines

Question 1

What cells produce histamine?

Answer 1

Mast Cells
Basophils
In brain and GI tract

Question 2

How is histamine involved with the allergic response?

Answer 2

Activated B-cells become plasma cells that produce IgE against the given allergen. IgE binds to mast cells and basophils by the Fc region and thereby sensitize these cells to the allergen. When the allergen cross-links these cells, it causes degranulation and release of histamine by increasing IP3 and Ca++. Also activates phospholipase A2 increasing platelet activating factor, LT’s, kinins

Question 3

What class of drugs may be helpful in decreasing degranulation of mast cells and basophils in response to an allergen?

Answer 3

Beta-2 agonist:

Isoproteronol, theophylline, epinephrine, cromolyn sodium