Immunology CH 11: Immunological Memory

What is a memory response?

(AKA a secondary immune response)

The immune response against second or subsequent exposure to an antigen

T/F: the primary immune response is activated faster and more effective

False, the memory response is activated faster than the primary immune response and it is more effective than the primary immune response

What are memory B cells?

Long lived B cells that differentiate from activated B cells during a primary immune response

How do memory B cells and naive B cells differ in terms of receptor affinity?

Naive B cells: express relatively low affinity IgM and IgD receptors on the surface

Memory B cells: express high affinity receptors on the surface because they were produced after activated B cells underwent somatic hypermutation and class switching.

What do memory T cells differentiate from?

They differentiate from activated T cells during a primary immune response

What are the 2 broad classes of memory T cells?

Effector memory T cells

Central memory T cells

Effector memory T cells:

Function similarly to effector T cells but have long lifespan and recall ability like memory T cells

Central memory T cells:

Act like naive T cells in that they need activation and move between blood and lymphoid tissues but have long lifespan and recall ability like memory T cells

How are naive B cells inhibited by IgG antibodies that were produced during a primary immune response?

Naïve B cells are inhibited by IgG antibodies from a previous immune response through Fcγ signaling. When they bind an antigen already coated with IgG, an inhibitory signal (that comes from IgG binding to Fcγ) stops them from activating. This ensures that memory B cells take over for a faster, stronger response instead.

How can the inhibition of naive B cells be beneficial to the immune response during a secondary immune response?

Inhibiting naïve B cells prioritizes memory B cells, ensuring a faster, stronger, and more efficient secondary immune response. This prevents weaker, redundant IgM antibody production and helps regulate immune activation.

What can be given to Rhesus Negative mothers during pregnancy to prevent a primary immune response against the rhesus positive fetal red blood cells?

An injection of IgG antibodies, called RhoGam, is given to the mother to prevent her immune system from forming antibodies against the rhesus D (RhD) antigen in the baby’s rhesus positive red blood cells.

What causes hemolytic anemia of a newborn?

The mother being rhesus negative and producing primary immune responses to the fetal red blood cells that are rhesus positive.

How does an injection of RhoGam work?

RhoGam contains anti-RhD antibodies that bind to any Rh-positive fetal cells in the mother's blood, preventing her immune system from recognizing them as foreign. This stops the activation of B cells and prevents the mother from forming antibodies against Rh-positive blood."

Original antigen sin:

the phenomenon where the immune system responds only to the original antigens of a pathogen, even if the pathogen has changed its surface antigens over time.

What does the original antigenic sin result in?

It results in a weaker immune response because the immune system can not effectively recognize and respond to new versions of the pathogen.

What is an example of an original antigenic sin?

The flu

In terms of the memory response and an original antigenic sin, the flu in particular, what does the phenomenon do to the response?

The memory response will focus on the original antigens from the first infection of the flu. If the pathogen changes its surface antigens over time (which the flu does every season), the memory response will be weaker because it doesn’t recognize the new antigens. This will result in a very weak response and probably the formation of a new primary immune response to the new surface antigens.