B Cell Immunity

Question 1

What are the 2 classes of B cells? Of those two classes, one can be further classified into 2 subcategories. What is this?

Answer 1

B1: Mucosa- limited Ag specificity
B2 cells: Can be divided into 2 major classes- Follicular B cells and Marginal B cells.

Follicular B cells: recirculating B cells (Majority)
Marginal B cells: reside in the spleen- blood borne polysaccharide Ags

Question 2

What is the function of ICOS/ICOSL?

Answer 2

These are essential for germinal center reaction (inducible co-stimulatory/homology with B7). This essentially means that these receptors are necessary to move the B cell and Tfh cell into the lymph node.

ICOS- Tfh cell

ICOSL- B cells

Question 3

What are the cell surface markers for plasma cells?

Answer 3

Decreased CD19 and CD20
Decreased HLA class II

Increased CD27

Question 4

What kinds of antigens do B1 cells respond to?

Answer 4

T-independent (non-protein) antigens in mucosal tissues

Question 5

What kind of antigens do B2 cells respond to?

Answer 5

Found in the spleen and recognize blood-borne polysaccharides

Question 6

Describe the antibody feedback system that is inhibiting.

Answer 6

IgG Abs made block further antibody production using the FCgammaRIIB receptor

Question 7

When antibodies are freely floating in the blood what happens when they bind to antigens?

Answer 7

Antigen bound antibodies will bind to Fc receptors in order to act as opsonins or to activate cells

Question 8

How are immunoglobulins removed from the blood and tissues?

Answer 8

Opsonization allows for the clearance of Immune complexes. CR1 on erythrocytes bind to the antibodies and transports them to the liver and spleen.

Phagocytes remove the immune complexes from the erythrocytes and allow them to continue circulating.

Question 9

What is passive immunization?

Answer 9

The introduction of antibody or antiserum into a naive recipient

Question 10

What is active immunization?

Answer 10

The introduction of an antigen that provokes an adaptive immune response

Question 11

Give 2 examples of passive immunization.

Answer 11

Snake bite anti-venom

Passive transfer of Ig from mother to child

Question 12

Give 2 examples of active immunization.

Answer 12

Natural exposure to pathogens

Vaccines

Question 13

What are 3 ways to evade humoral immunity?

Answer 13

Change of surface antigens- HIV

Outer capsule or coat prevents complement activation

Capsule prevents binding of antibodies and phagocytosis- Streptococcus

Question 14

What is the main T-independent Marginal Zone antibody produced?

Answer 14

IgM

Question 15

What antibodies are produced from T-dependent Follicular B cells?

Answer 15

IgG
IgA
IgE

*Note that this requires isotype switching