Innate Immunity Overview

The first line of defense against pathogens. These barriers prevent microbes from entering the body and causing infection.

The second line of defense that acts rapidly after pathogens breach the physical barriers. It is non-specific and targets a wide range of pathogens.

A group of proteins that work together to form a pore in the bacterial membrane, causing the bacteria to lyse and die.

Small antimicrobial peptides that kill bacteria by forming pores in their membranes.

The property of a molecule that has both hydrophobic and hydrophilic regions. This property allows defensins and complement proteins to interact with both water and cell membranes.

The property of a molecule that has a positive charge. This property allows defensins and complement proteins to interact with negatively charged bacterial membranes.

A group of cells that are part of the innate immune system and are involved in the recognition and destruction of pathogens. Examples include macrophages, neutrophils, and NK cells.

A type of immune cell that responds quickly to infection. It releases cytokines that activate other immune cells and help to control infection.

Innate immune cells, such as macrophages, release these molecules to trigger inflammation and attract other immune cells to the site of infection or injury.

A type of innate immune cell that detects and responds to microbes, initiating inflammation and promoting tissue repair.

Macrophages differentiate into different functional states based on the environment they are in, allowing them to carry out specialized tasks such as killing bacteria or promoting tissue repair.

A type of innate immune receptor expressed by macrophages that recognizes specific molecules found on microbes.

Cytokines that are released by macrophages in response to microbial detection, triggering inflammation and activating other immune cells.

A process initiated by macrophages that involves the recruitment of immune cells and the release of inflammatory mediators, leading to redness, swelling, and pain at the site of infection or injury.

Macrophages can differentiate into states that promote tissue repair, such as by producing molecules that help to rebuild damaged tissue and restore normal function.

A type of cell-to-cell communication where immune cells directly interact with each other through physical contact and signaling pathways.

Pattern Recognition Receptors (PRRs) are proteins expressed by immune cells that recognize conserved molecular patterns found on pathogens. These receptors initiate an immune response by sensing the presence of a microbe.

Mast cells are immune cells found in tissues throughout the body, especially near blood vessels and nerves. Upon activation, mast cells release histamine and other substances that cause inflammation by widening blood vessels and attracting white blood cells to the site of infection.

Neutrophils are the most abundant type of white blood cell or leukocyte. They are phagocytic cells that ingest and destroy microbes, particularly bacteria. They are short-lived cells with a lifespan of only a few days.

Neutrophils are produced in the bone marrow and stored there until they are needed. They circulate in the blood and are recruited to sites of infection via chemoattractants like IL-8.

Neutrophils possess three types of granules: primary, secondary, and tertiary. These granules contain a range of preformed mediators that are released during the inflammatory response. These mediators can kill microbes and activate other immune cells.

The recruitment of neutrophils to the site of infection involves a multi-step process. The steps include: 1) Rolling: Leukocytes weakly adhere to the endothelium, 2) Firm adhesion: leukocytes firmly adhere to the endothelium 3) Transmigration: leukocytes cross the endothelium 4) Chemotaxis: leukocytes travel to site of infection along a chemical gradient

Dendritic cells are specialized antigen-presenting cells (APCs) that play a crucial role in initiating adaptive immune responses. They are located in tissues throughout the body and are highly efficient at collecting and presenting antigens to T cells

Dendritic cells are unique in their ability to mature and migrate from tissues to lymph nodes where they activate T cells. This process involves a change in their phenotype and function: they become efficient at antigen presentation and T cell activation.