Immunology - 14

Question 1

What are the characteristics of IgM?

Answer 1

• Found in monomeric (BCR) and polymeric (secreted pentamer = serum) forms
• default antibody (1st to be produced in the life of a B cell)
• found on all naïve B cells as the BCR
• Pentameric structure is good at activating complement
• only type made by a fetus

Question 2

What are the characteristics of IgD?

Answer 2

• Found almost exclusively on the surface of naïve B cells (it acts as a BCR)
• the least common Ig made (you cannot find secreted IgD)

Question 3

What are the characteristics of IgG?

Answer 3

• Jobs: complement, opsonization, neutralization
• most predominant isotype and tissues (small size allows it to easily cross the vasculature and endothelium)
• only isotype the crosses the placenta (effective titers until approximately six months)
• 4 subtypes (don’t need to know them)

Question 4

What are the characteristics of IgA?

Answer 4

• Really, really important for mucosal immunity
• found in mucosa and that secretions (tears, saliva, mucus, sweat, colostrum) - protective for infants who are breast-fed (passed from mom)
• can be monomeric or dimeric

Question 5

What are the characteristics of IgE?

Answer 5

• Jobs: ALLERGY! all is bound to the high affinity Fc receptors on mast cells, basophils, and eosinophils

Question 6

In a two-month-old baby, what isotype would you find?

Answer 6

IgM