Adaptive Immunity Lecture

Immune cells that engulf and break down pathogens, displaying fragments of the pathogen (antigen) on their surface using MHC molecules.

Group of genes that code for proteins on the surface of cells that present antigens to T cells. Two classes, MHC I and MHC II, present antigens to different types of T cells.

MHC molecules bind to processed antigens and display them on the surface of antigen-presenting cells (APCs), allowing T cells to recognize and respond to the antigen.

1. Antigen enters the body. 2. APC (like macrophages) engulf the antigen. 3. The antigen breaks down into small particles. 4. These particles are transported to the cell surface. 5. They are displayed on the cell surface bound to MHC molecules.

Type of T cell that suppress the immune response, preventing overreaction and autoimmune diseases. They help maintain immune system balance.

T cells that activate other immune cells, like B cells and cytotoxic T cells, by releasing signaling molecules called cytokines.

T cells that directly kill cells infected with viruses or bacteria, or abnormal cells (like cancer cells), by releasing toxic substances like perforin and granzyme.

A mechanism used by cytotoxic T cells to kill target cells. Perforin creates pores in the target cell membrane, allowing granzyme to enter and trigger apoptosis (programmed cell death).

Type of immune cell that produces antibodies (proteins that specifically bind to antigens). They are responsible for humoral immunity.

Type of immune response mediated by antibodies produced by B cells in the blood and lymph. It protects against extracellular pathogens and toxins.

A specific, acquired immune response that develops throughout life, unlike innate immunity, which is present at birth. It's slower to respond but highly specific to individual antigens and possesses memory function.

The three key principles of adaptive immunity: Recognize - the immune system identifies specific antigens. Respond - it mounts a targeted response like cytokine production or antibody generation. Remember - it retains memory of past invaders, leading to faster responses on subsequent exposures.

The primary cells of adaptive immunity, responsible for specific antigen recognition. They are categorized into two main types: B lymphocytes (B cells) and T lymphocytes (T cells).

A key process in adaptive immunity where a specific lymphocyte, with a receptor matching a particular antigen, is activated and proliferates to create a clone of identical cells. This ensures a targeted immune response against the specific antigen present.

The process by which immune cells, like macrophages and dendritic cells, break down and display antigens on their surface to T lymphocytes. This allows T cells to recognize and respond to foreign invaders.

A crucial part of adaptive immunity involving T lymphocytes that primarily targets infected cells or cancerous cells. It directly kills infected cells and regulates other immune responses.

An arm of adaptive immunity involving B lymphocytes that primarily combats pathogens in body fluids. B cells produce antibodies, which bind to and neutralize pathogens.

Specialized proteins produced by B lymphocytes that bind to specific antigens, thereby neutralizing pathogens. They have a Y shape with a specific antigen binding site.

B cells produce antibodies with the same specificity as their B cell receptor (BCR).

Antibodies are also known as immunoglobulins (Igs) or gamma globulins (g-globulins).

Antibodies consist of two heavy chains and two light chains arranged in a Y-shaped structure. Two identical branches form the antigen-binding sites (Fab), and the stem is called the constant fragment (Fc).

The Fc fragment of an antibody binds to Fc receptors on cells, which then trigger the physiological effects of the antibody.

There are five types of heavy chains (g, m, a, d, e), which give rise to five different antibody isotypes.

IgG is the most abundant antibody in circulation, making up 70-75% of circulating immunoglobulins.

IgM exists as a pentamer, meaning it has five antibody units joined together.

IgA is found in secretions, such as saliva, mucus, and breast milk. It often exists as a dimer, with two antibody units linked.

IgG is the only antibody that is transported across the placenta from mother to fetus, providing passive immunity to the newborn.

IgD is found on the surface of B cells and plays a role in B cell activation.