BIOG251 Chapter 13.2: Adaptive Immunity

Helper T cell activation

Antigen-presenting cells associated with MHC II are present

Helper T cell function

Activate the other immune cells

Cytotoxic T cell activated

Antigen presenting cells or infected nucleated cells presenting antigens associated with MHC I are present

Cytotoxic T cell function

Destroy cells infected with intracellular pathogens

Cytotoxic T cells produce __________ and __________ that invade the infected cell and induce apoptosis

perforin : granzymes

Antigen producing cells and T cells release __________ to fully activate helper T cells

Cytokines

Positive selection of B cells

B cells without a functional receptor undergo apoptosis

Negative selection of B cells

B cells with BCRs that strongly bind to self-antigens are destroyed

Memory B cells

Stay in the body for an extended period of time and provides immunological memory

Plasma cells

Specialized for antibiotics production

The _____ and ________ support the synthesis and secretion of large amounts of antibodies

ER : golgi

IgG

Most abundant, crosses placenta to fetus, activates complement, opsonizes pathogens

IgA

Found in mucosal secretions, prevents pathogen attachment, secreted through breast milk

IgM

First antibody in primary immune response, effective at agglutination, strong activator of complement

IgD

Found on the surface of B cells, helps activate B cells

IgE

Involved in allergic reactions, defense against parasites

Every antibody has at least how many binding sites?

2

How do antibodies act as antitoxins?

They directly bind to the toxin

What do antigen-antibody complexes activate?

The complement system

When are helper T cells activated?

When an antigen presenting cells shows a foreign antigen on MHCII

Specialized B cells

Plasma or memory cells

B Cell activation steps

Recognition of antigen → antigen binding of B cell receptor → internalization of antigen → antigen presentation → interaction with helper T cells → co-stimulation and activation signal → clonal expansion and differentiation

B cell receptor

Membrane-bound antibody molecule on the surface of B cells

Internalization of antigen

The antigen-BCR complex is internalized into the B cell via endocytosis

The bridging of antigens allows soluble antibodies to __________________, enhancing phagocytosis

Clump cells or bacteria together

B cell maturation

Must undergo positive and negative selection

BCR

B cell receptor antibody bound to the membrane of the B cell’s surface

How does Measles trigger immunity amnesia?

Memory cells are eliminated, causing the body to forget how to respond to the disease

Agglutination enhances which cell type?

Phagocytes

What can happen when the Fc region is exposed?

Phagocytes with an Fc receptor bind to the Fc portion of an antibody

When multiple receptors bind at the same time, what is triggered?

Engulfment

Primary immune response

Cloned B cells are differentiated into memory B cells programmed to respond to subsequent exposures

Secondary immune response

Quick response to disease, antibodies and plasma cells are plentiful and attack the disease

When are there the most antibodies present?

The secondary immune response