C17L7 Acquired Immunity: T Cells, B Cells and Antibodies

Acquired Immunity

An immune response to a specific pathogen that can be reactivated upon subsequent encounters with the same pathogen.

Lymphocytes

White blood cells that are the key players in the acquired immune system, specifically recognizing and responding to antigens.

Antigen

A molecular structure recognized by the immune system, which triggers an immune response.

T Lymphocyte (t cells)

T cells mature in the Thymus

Cytotoxic T Lymphocyte (CTL)

lymphocyte that destroys infected cells before they release mature parasites

B Lymphocytes (b cells)

b cells mature in the Bone marrow

Helper T Cells (Th cells)

Also known as CD4 T cells, they activate other lymphocytes and play a regulatory role in immune responses.

Antigen-Presenting Cells

Cells that express foreign antigens with MHC 2 molecules and are important for the activation of T and B cells.

MHC 1 Molecule

A molecule that presents antigens on a cell's surface, allowing CD8 T cells to identify infected cells.

MHC 2 Molecule

A molecule that presents antigens on antigen-presenting cells, allowing helper T cells to become activated.

B Cells

lymphocytes that are capable of producing antigen specific antibodies, once activated it proliferates to produce lots of active b cells most of which then become antibody factories that secrete up to 2000 antibodies per second

Antibodies

Proteins produced by B cells that specifically recognize and bind to antigens.

Functions of Antibodies

Neutralization, marking pathogens for phagocytosis, causing agglutination, and stimulating complement formation.

Proliferation of B Cells

The process by which activated B cells multiply to produce many copies that secrete antibodies.

Fc Domain of Antibody

The part of the antibody that does not bind to antigens but is important for other antibody functions.

Neutralization (the first main function of an antibody)

if enough antibodies attach to a pathogen they can completely coat it and block it from interacting with the body’s cells

Mark Pathogens for phagocytosis (the second main function of an antibody)

When an antibody binds to a pathogen, the antigen-binding sites face the pathogen, which leaves the Fc domain sticking out from the side of the pathogen. Not only that, but when an antibody is bound to its antigen, the structure of the Fc domain changes to a structure that receptors on neutrophils and macrophages recognize as a signal to phagocytize whatever the antibody is bound to.

Agglutination

or binding of pathogens together in clumps due to the fact that antibodies have two binding sites, each of which could bind to separate pathogens and join them together. These clumps of pathogens are easier for cells to phagocytize as a group rather than one at a time.

Whan can antibodies bound to a pathogen stimulate?

complement formation of membrane attack complexes and kill pathogens that way.

Th1 Cells

A subset of helper T cells that activates CD8 T cells in response to specific antigens.

Th2 Cells

A subset of helper T cells that activates B cells.

Peptides

Small sequences of amino acids derived from proteins that are displayed by cells on MHC molecules.