Madi, Anumita, Carlos, and Annika Phagocytes Madi, Anumita, Carlos, and Annika

What are Phagocytes? Eukaryotic Cells in the human body Protect the body from pathogens by the process of Phagocytosis Part of the inflammatory response Derive from stem cells in the bone marrow Move by a method called Chemotaxis

What do Phagocytes do? “Eat up” or “Engulf” pathogens through Phagocytosis Use the proteins from the pathogens previously engulfed to protect the body from future pathogens They help initiate an immune response

Neutrophils White blood cell 50%-80% of all white blood cells in the body are neutrophils Mediate immune responses against infectious microorganisms Travel to the site of infection through a process called chemotaxis Granules on the cell contain various agents for killing microbes Release enzyme Kallikrein catalyzes Bradykinins (promote vasodilation) Short Life Span (Few hours - Few days)

Eosinophils White Blood Cell Mediate Allergic Responses 1-4% of WBC’s Mediate Allergic Responses Digest cellular debris and pathogens tagged with antibodies; can attack larger pathogens like parasites via exocytosis. Used in many inflammatory responses, especially allergic reactions

Macrophages Located in Strategic Locations around the body. Are produced during the differentiation of monocytes. Rid the body of old cells, present antigens, and regulate immune responses. An amoeba like cell capable of identifying, surrounding, engulfing, and digesting pathogens. Activated by cytokines (cell signaling proteins)

Monocytes Produced by Bone Marrow. Biggest type of white blood cell in the immune system. Help to protect against diseases and other infection. They have the ability to become Macrophages before they attack any germs in the body. When in the form of a Macrophage, they consume and kill any harmful bacteria, viruses, and fungi.

Dendritic Cells Antigen-Presenting Cells process antigen material and present it on the surface of the T-cell Act as messengers between the two immune systems Present in tissues in contact with the external environment Process antigen material and present it on the cell surface Found in the skin, nose, lungs, stomach, and intestines

B-Lymphocyte White Blood Cells 10-20% of Lymphocytes are B-Lymphocytes Create and Secrete Antibodies Once Presenting Antibodies, called “Plasma Cells” Mature in Bone Marrow Mediate Humoral Immunity (Production of Antibodies)

How do Phagocytes contribute to immunity? Phagocytes have receptor cells to respond to invading cells Once “connected” to the invading cells, the Phagocyte will “engulf” the pathogen by completely surrounding the pathogen Once “engulfed”, the pathogen is is inside the cell in a vesicle, called a phagosome Lysosomes dump their contents into the vesicle, which breaks down the pathogen into proteins, molecules, and peptide chains The MHC (major histocompatibility complex) protein presents the peptide chains onto the cell’s surface for specific immunity proteins to respond to

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