Chapter 7 ( Humoral Immunity )

Question 1

The most effective antibody at activating complement ?

Answer 1

IgM

Question 2

Why IgM cant act as opsonin or a mediator of ADCC ?

Answer 2

Because its incapable of binding to cellular Fc receptors

Question 3

X-linked hyper IgM syndrome defect ? Peripheral blood findings ?

Answer 3

Mutation in the gene encoding the CD40 ligand on X chromosome

High level of IgM
Autoantibodies to neutrophils , platelets and RBCs

Question 4

Characteristics of IgG ?

Answer 4

1- activates complement
2- act as opsonin
3- mediates ADCC
4- neutralize pathogens and toxins

Question 5

IgA characteristics ?

Answer 5

A neutralizing antibody by inhibiting the binding of toxins or pathogens to the mucosa of the digestive , respiratory and urogenital system

Question 6

How the pathogens infecting the mucosa induces IgA production ?

Answer 6

By the secretion of :
TGF-beta by the infected cells
IL5

Question 7

Function of the complement cascade in adaptive immunity ?

Answer 7

Removal of extracellular invader

Concentration of antigens into the secondary lymphoid organs where the adaptive immune response is elicited

Question 8

Presentation of patients with B lymphocytes deficiencies ?

Answer 8

Recurrent pyogenic infections with extracellular pathogens