LEC 15 LEUKAROCYTES

What is a lymphocyte?

cells that produce antibodies

to kill pathogens

that invade the body

Two types of lymphocytes

T cells = direct combat with viruses

B cellls = make antibodies

Two main classes of lymphocytes

B cells and T cells.

Where do B cells originate from?

Bone marrow.

A B cell that has not been presented to an invader is called a?

Virgen B cell

After a B cell has been introduced to an invader, it matures into a?

Plasma cell.

What does a mature plasma cell produce?

Antibodies.

After the infection is over, plasma cells mature into what?

Memory cells.

Where do T cells originate?

Thymus gland.

What do T cells attack directly?

Foreign cells, including organ transplants.

What does a B cell mature into after being presented with an antigen?

Plasma cell.

Function of a plasma cell

Secrete antibodies.

Function of antibodies from plasma cells

Kill or neutralize attacking pathogens.

How do plasma cell antibodies kill attacking cells?

They attach to bacteria and can damage their cell membrane.

How do plasma cell antibodies help fight encapsulated bacteria?

They attach to encapsulated bacteria to help neutrophils and macrophages phagocytize them.

How do antibodies agglutinate bacteria?

They clump around bacteria and bind receptor sites so the bacteria cannot cause harm.

Define mononucleosis

A disorder of B-cell lymphocytes.

Cause of mononucleosis

Epstein-Barr virus.

Characteristic of mononucleosis

Inflammation of lymph vessels (lymphangitis).

What is lymphangitis?

Lymph vessel inflammation, usually from infection.

Visual characteristic of mononucleosis

Infected lymphocytes have a scalloped edge where they touch RBCs.

Function of a T cell

Coordinate the immune response by recruiting other white blood cells.

How does a T cell directly destroy bacteria?

By damaging the cell membrane.

How does a T cell directly destroy a foreign cell?

By damaging the cell membrane.

What type of cell kills virus-infected host cells?

T cell.

Characteristics of T cells when killing invading cells

They do not need to phagocytize the invading cell; they kill it and macrophages dissolve the debris.

Relationship between T cells and antibodies

T cells do not need antibodies to destroy invading cells.

Which patients are at risk due to T-cell function?

Organ transplant patients.

What type of cell attacks transplanted organs?

T cells.

What drugs inhibit T-cell action?

Immunosuppressive drugs.

What cell is attacked by HIV (AIDS)?

T cells.

Where do T cells originate?

Thymus gland.

What does the thymus gland secrete?

Hormones that help T cells become immunocompetent.

What happens when a T cell becomes immunocompetent?

It matures and becomes functional.

Three types of T cells

Cytotoxic (killer)

Helper

Suppressor T cells.

Function of Cytotoxic (killer) T cells

Directly kill bacteria or infected host cells.

Functions of Helper T cells

Release cytokines to recruit white blood cells

present macrophage antigens to B cells

What happens when a T cell presents a macrophage antigen to a B cell?

The B cell produces antibodies against that specific pathogen.

Functions of Suppressor T cells

Stop the immune response when it is over

tell plasma cells to remember how to destroy a specific pathogen

What type of B cell remembers pathogens?

Memory B cells.

Function of Memory B cells

React faster when the same pathogen invades again.

Why can Memory B cells react faster?

They already have the proper antibodies stored for that pathogen.

True or False: B cells touch surface antigens to make a copy of their shape.

False. Helper T cells recognize and interact with presented antigens.

Which cell is presented the surface antigen?

Helper T cells.

B cells create ______ against pathogens.

Antibodies.

True or False: Helper T cells multiply and have two main roles.

True.

Helper T cells activate which cells?

B cells and Killer T cells.

What do Helper T cells tell B cells to do?

Helper T cells tell B cells

how to neutralize the pathogen

by responding to presented bacterial antigens.

What do B cells turn into?

Plasma cells.

Plasma cells produce ______ to ______ a specific pathogen.

Antibodies; neutralize.

Second role of Helper T cells

Activate Killer T cells.

What do Killer T cells secrete to recruit other WBCs?

Cytokines.

True or False: Killer T cells can destroy the pathogen itself (bacteria).

True.

Why would a Killer T cell destroy an entire body cell?

Because the body cell is infected with a virus.

When the immune response is over, what cell stops the process?

Suppressor T cells.

What do Suppressor T cells tell some B cells (plasma cells) to do?

Remember how to destroy that specific pathogen.

B cells (plasma cells) become what?

Memory B cells.