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Mast Cells: Granulated cells that are found in almost all tissues, most abundantly in the skin and the gastrointestinal tract. Like the Basophils, mast cells contain large amounts of Histamine and Heparin. Unlike basophils, mast cells normally remain in the tissues and do not circulate in the blood. Mast cells, derived from the bone marrow stem cells, are regulated by the Stem cell factor.

Inflammation

JoVE 10902

In response to tissue injury and infection, mast cells initiate inflammation. Mast cells release chemicals that increase the permeability of adjacent blood capillaries and attract additional immune cells to the wound or site of infection. Neutrophils are phagocytic leukocytes that exit the bloodstream and engulf invading microbes. Blood clotting platelets seal the wound and fibers create a scaffold for wound healing. Macrophages engulf aging neutrophils to end the acute inflammatory response. Tissue injury and infection are the primary causes of acute inflammation. Inflammation protects the body by eliminating the cause of tissue injury and initiating the removal of cell debris resulting from the initial damage and related immune cell activity. Inflammation involves mediators of both the innate and adaptive immune system. Proper regulation of inflammation is crucial to clear the pathogen and remove cell debris without overly damaging healthy tissue in the process. If inflammatory processes are not properly regulated, chronic inflammation can arise that is often fatal. Mast cells are the first to respond to tissue injury, as they are primarily located in areas that have contact with the exterior: the skin, gut, and airways. Mast cells have an arsenal of receptors on their cell surface and can hence be activated by a wide variety of stimuli, such as mi

 Core: Immune System

Allergic Reactions

JoVE 10901

We speak of an allergy when the immune system triggers a response against a benign foreign structure, like food, pollen or pet dander. These elicitors are called allergens. If the immune system of a hypersensitive individual was primed against a specific allergen, it will trigger allergic symptoms during every subsequent encounter of the allergen. Symptoms can be mild, such as hay fever, to severe, such as potentially fatal anaphylactic shock. The immune system is crucial for defending an organism against bacteria, viruses, fungi, toxins, and parasites. However, in a hypersensitive response, it can be triggered by harmless substances and cause unpleasant or potentially life-threatening overreactions, called allergies. The first step toward establishing an allergy is sensitization. For instance, an individual becomes allergic to the pollen of ragweed when, for the first time, immune cells in the respiratory passage take up the pollen and degrade the allergens into fragments. These immune cells are called antigen-presenting cells, or APCs, because they display the degraded allergen fragments on their surface. Examples of APCs are dendritic cells, macrophages and B cells. Subsequently, APCs activate encountered Type 2 helper T cells (Th2). The activated Th2 then release chemical signals (e.g., cytokines) that cause B cells to differen

 Core: Immune System

Antibody Structure

JoVE 10898

Antibodies, also known as immunoglobulins (Ig), are essential players of the adaptive immune system. These antigen-binding proteins are produced by B cells and make up 20 percent of the total blood plasma by weight. In mammals, antibodies fall into five different classes, which each elicits a different biological response upon antigen binding.

Antibodies consist of four polypeptide chains: two identical heavy chains of approximately 440 amino acids each, and two identical light chains composed of roughly 220 amino acids each. These chains are arranged in a Y-shaped structure that is held together by a combination of covalent disulfide bonds and noncovalent bonds. Furthermore, most antibodies carry sugar residues. The process of adding sugar side chains to a protein is called glycosylation. Both the light chain and heavy chain contribute to the antigen binding site at each of the tips of the Y structure. These 110-130 amino acids are highly variable to allow recognition of an almost unlimited number of antigens. This region is also called the variable region and is part of the antigen binding fragment. Each arm of the Y-shaped unit carries an identical antigen binding site. Antibodies can crosslink antigens: when one arm binds to one antigen and the other arm binds to a second, structurally identical antigen. Crosslinking is facilitated by the f

 Core: Immune System

What is the Immune System?

JoVE 10895

The immune system comprises diverse biological structures and processes that protect the body from disease. These processes can be classified into innate and adaptive immunity. To work effectively, the immune system needs to detect pathogens by distinguishing the body’s own structures from foreign elements. If this determination fails, autoimmune diseases occur in which the immune system reacts against the body’s own tissue. The innate immune system is the first line of defense against infection. It comprises physical barriers and a variety of cells that act quickly and non-specifically against elements that are foreign to the host (i.e., non-self). Examples of physical barriers in mammals are skin, the lining of the gastrointestinal tract, and secretions, such as mucus or saliva. Once an invader overcomes physical barriers, cells of the inflammatory response are recruited to the entry site: mast cells release a plethora of chemicals that attract other cells of the innate immune system and activates the adaptive immune system. Phagocytic cells, such as neutrophils and macrophages, ingest and destroy pathogens. Natural killer cells, a special type of white blood cell, destroy virus-infected cells. Together, cells of the innate immune system eradicate the invader or hinder its spread, and activate the adaptive immune system. How can an organism

 Core: Immune System

Nociception

JoVE 10873

Nociception—the ability to feel pain—is essential for an organism’s survival and overall well-being. Noxious stimuli such as piercing pain from a sharp object, heat from an open flame, or contact with corrosive chemicals are first detected by sensory receptors, called nociceptors, located on nerve endings. Nociceptors express ion channels that convert noxious stimuli into electrical signals. When these signals reach the brain via sensory neurons, they are perceived as pain. Thus, pain helps the organism avoid noxious stimuli. The immune system plays an essential role in pain pathology. Upon encountering noxious stimuli, immune cells such as mast cells and macrophages present at the site of injury release inflammatory chemicals such as cytokines, chemokines, histamines, and prostaglandins. These chemicals attract other immune cells such as monocytes and T cells to the injury site. They also stimulate nociceptors, resulting in hyperalgesia—a more intense response to a previously painful stimulus, or allodynia—a painful response to a normally innocuous stimulus such as light touch. Such pain sensitization helps protect the injured site during healing. In some cases, pain outlives its role as an acute warning system if sensitization fails to resolve over time. Chronic pain—persistent or recurrent pain lasting longer than t

 Core: Musculoskeletal System

Intracellular Staining and Flow Cytometry to Identify Lymphocyte Subsets within Murine Aorta, Kidney and Lymph Nodes in a Model of Hypertension

1Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, 2Department of Molecular Physiology and Biophysics, Vanderbilt University, 3Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University

JoVE 55266

 Immunology and Infection

Isolation of Lamina Propria Mononuclear Cells from Murine Colon Using Collagenase E

1Department of Pediatrics, Division of Hematology / Oncology and Bone Marrow Transplantation, University of Miami Miller School of Medicine, 2Batchelor Children's Research Institute, University of Miami Miller School of Medicine, 3Department of Microbiology & Immunology, University of Miami Miller School of Medicine, 4Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, 5Holtz Children's Hospital, University of Miami Miller School of Medicine

JoVE 59821

 Immunology and Infection

Imaging FITC-dextran as a Reporter for Regulated Exocytosis

1Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, 2Department of Pathology, Sackler Faculty of Medicine, Tel Aviv University, 3Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, 4Departments of Pathology and of Microbiology and Immunology and Sean N. Parker Center for Allergy and Asthma Research, School of Medicine, Stanford University

JoVE 57936

 Biology

Combined Intravital Microscopy and Contrast-enhanced Ultrasonography of the Mouse Hindlimb to Study Insulin-induced Vasodilation and Muscle Perfusion

1Laboratory for Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center, 2Department of Internal Medicine, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center

JoVE 54912

 Medicine

Perturbations of Circulating miRNAs in Irritable Bowel Syndrome Detected Using a Multiplexed High-throughput Gene Expression Platform

1Digestive Disorders Unit, National Institute of Nursing Research, National Institutes of Health, DHHS, 2National Institutes of Health Research Scholar, Howard Hughes Medical Institute, 3Internal Medicine, Medical School, University of Michigan

JoVE 54693

 Genetics

Early Viral Entry Assays for the Identification and Evaluation of Antiviral Compounds

1Department of Chinese Medicine, Taipei Medical University Hospital, 2Department of Obstetrics and Gynecology, School of Medicine, College of Medicine, Taipei Medical University, 3Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, 4Division of Hematology and Oncology, Department of Internal Medicine, Taipei Medical University Hospital, 5Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, 6Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University

JoVE 53124

 Immunology and Infection

Surgical Models of Gastroesophageal Reflux with Mice

1Department of Thoracic Surgery, Ningxia Medical University General Hospital, 2Cancer Research Program, North Carolina Central University, 3Department of Thoracic & Cardiovascular Surgery, The First Affiliated Hospital of Chongqing Medical University, 4Department of Medicine, Center for Esophageal Disease and Swallowing, Division of Gastroenterology and Hepatology, University of North Carolina at Chapel Hill

JoVE 53012

 Medicine

Isolation of Leukocytes from the Murine Tissues at the Maternal-Fetal Interface

1Department of Obstetrics & Gynecology, Wayne State University School of Medicine, 2School of Paediatrics and Reproductive Health, Research Centre for Reproductive Health, the Robinson Research Institute, The University of Adelaide, 3Department of Immunology & Microbiology, Wayne State University School of Medicine, 4Perinatology Research Branch, NICHD/NIH/DHHS

JoVE 52866

 Immunology and Infection

Investigating Mast Cell Secretory Granules; from Biosynthesis to Exocytosis

1Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, 2Division of Allergy and Immunology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, 3Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University

JoVE 52505

 Immunology and Infection
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