Lecture 9 — Adaptive Immunity

A specific immune response that develops after exposure to an antigen.

Some pathogens can evade innate defenses, so the body needs a more targeted response.

Specificity, inducibility, memory, and tolerance to self.

The immune system recognizes particular antigens or epitopes.

The response must be activated by exposure to a specific antigen.

The ability to respond more quickly and strongly after encountering an antigen again.

To prevent the immune system from attacking the body's own cells and tissues.

An autoimmune disorder can develop.

Humoral immunity and cell-mediated immunity.

Antibody-mediated immunity that uses antibodies circulating in body fluids.

B lymphocytes that differentiate into plasma cells.

Adaptive immunity that uses T cells to recognize and act against infected or abnormal cells.

T lymphocytes, especially cytotoxic T cells.

Extracellular pathogens and toxins.

Intracellular pathogens.

They recognize and kill infected or abnormal host cells.

It can recognize and destroy cells displaying abnormal or tumor-associated antigens.

It may recognize donor tissue as foreign and attack it.

A substance recognized by the immune system.

The specific part of an antigen that an immune receptor recognizes.

Yes. Different parts of one antigen can be recognized separately.

An antigen-binding receptor attached to the surface of a B cell.

It is structurally similar to an antibody but remains attached to the B-cell surface.

A receptor on a T cell that recognizes a specific antigen fragment presented by an MHC protein.

Major histocompatibility complex.

They display antigen fragments on cell surfaces for T-cell recognition.

On nearly all nucleated cells in the body.

Red blood cells and sperm cells.

Endogenous antigens from inside the cell.

CD8-positive cytotoxic T cells.

MHC class I.

Exogenous antigens taken up from outside the cell.

Professional antigen-presenting cells, including dendritic cells, macrophages, and B cells.

CD4-positive helper T cells.

MHC class II.

A cell that processes antigens and displays antigen fragments on MHC proteins.

The ability of dendritic cells to present exogenous antigens on both MHC class II and MHC class I.

It allows dendritic cells to help activate cytotoxic T-cell responses to antigens taken up from outside the cell.

Lymph nodes.

The multiplication of an activated lymphocyte to produce many cells with the same antigen specificity.

It becomes activated and can help coordinate an adaptive immune response.

They recognize matching antigen presented by B cells and provide activating signals.

It undergoes clonal expansion and differentiates into plasma cells and memory B cells.

A differentiated B cell that secretes antibodies.

A long-lived B cell that helps produce a faster response after future exposure to the same antigen.

Antigens that can activate B cells without helper T-cell assistance.

Some long, repeating polymers such as bacterial capsules and flagella.