specific immune response

which cells can be antigen presenting cells?

• macrophages

• neutrophils

• B lymphocytes

• cells infected by a virus/cancer cells

explain the process of antigen presentation in B lymphocytes:

• have a specific antibody w/ a shape complementary to pathogen’s antigens

• pathogen is endocytosed then processed

• antigens presented on cell surface

explain antigen presentation in cells infected by a virus/cancer cells:

present viral/tumour (respectively) antigens on surface

who are antigens presented to and why?

T helper cells - have a receptor complementary to pathogen

what is the function of T helper cells?

• stimulate further phagocytosis

• stimulate division of cytotoxic T lymphocytes

• stimulate division of B lymphocytes

• develop into memory T cells for future infection

what is the function of cytotoxic T lymphocytes?

• seek out cells w/ foreign antigens (antigen presenting cells)

• destroy pathogenic cells by releasing perforin into invaded cell

• perforates cell wall

• → cell dies due to osmotic lysis

what is the specific immune response?

lymphocytes carry out a specific attack on pathogen

what are the key features of the T lymphocyte?

• matures in thymus

• responds to antigens presented on surface of cells

• performs cell mediated response

what are the key features of the B lymphocyte?

• matures in bone marrow

• responds to free antigens found in blood plasma and tissue fluid

• performs humoural response

what is the function of the cell mediated response?

produces cytotoxic T lymphocytes that destroy infected body cells to reduce pathogen spread

why does the cell mediated response have its name?

is triggered by body’s own cells

what is the function of the humoral response?

produces antibodies complementary to antigen

explain the cell mediated response:

• antigen enters body and is presented by complementary B lymphocytes/macrophages/neutrophils/infected cells

• complementary T helper lymphocytes bind to presented antigen

• complementary T lymphocytes stimulated to reproduce by mitosis

• some T lymphocytes become memory T lymphocytes/cytotoxic T lymphocytes or some stimulate further phagocytosis

explain the humoral response:

• antigen enters body and is presented by complementary B lymphocytes/macrophages/neutrophils/infected cells

• complementary T helper lymphocytes bind to presented antigen

• complementary B lymphocytes stimulated to reproduce by mitosis

• some B lymphocytes become memory B lymphocytes/plasma lymphocytes (which make complementary antibodies)

what is clonal selection?

the process of matching the antigens on an antigen presenting cell w/ the antigen receptor on the B and T receptors

what is clonal expansion?

the process of stimulating the selected B/T lymphocytes to divide by mitosis