Cell recognition and the immune system

What are the cells that distinguish between self cells and non-self cells called?

Lymphocytes

What are the 4 molecules lymphocytes can identify?

1. Pathogens

2. Cells from other organisms of the same species

3. Abnormal body cells

4. Toxins

Define an antigen

A molecule, typically a protein, which triggers an immune response when detected in the body

What are the 2 main types of white blood cells?

Phagocytes and lymphocytes

Where are phagocytes located?

• Blood

• Tissues

Define antigen presenting cell

Any cell that presents a non-self antigen on their surface

Give the 4 categories of antigen presenting cells?

• Infected body cells

• Phagocyte (which has engulfed pathogen)

• Cells from transplanted organ

• Cancer cells (abnormal shaped self-cell antigen)

Where are lymphocytes made?

Bone marrow

Where are T Lymphocytes matured?

Thymus

Why does ‘Cell mediated response’ have its name?

T cells only respond to the antigens on antigen presenting cells

What cloned helper T cells differentiate into?

• Memory cells

• Cytotoxic T cells

• Remain as helper T cells (to activate B lymphocytes and stimulate phagocytes)

What do cytotoxic T cells release?

The protein perforin

What does perforin do?

1. Embeds in cell surface membrane

2. Creates pore

3. Substances can enter/leave the cell

4. Cell dies :(

Where do B lymphocytes mature?

Bone marrow

Outline the humoral response

Response which involves B cells and antibodies

What can B cells differentiate into?

• Plasma cells (make antibodies)

• B memory cells

What protein structure does an antibody have?

Quaternary protein structure (4 polypeptide chains)

What is agglutination?

• Antigen-antibody complexes form

• Clumps antigens together

• Easier for phagocytes to find and destroy pathogens