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1 Immunology Review Notes [1.24.05] Lecture 1 Innate Immunity 1. Anatomical barriers a. Skin i. 15 layers of cells are dead/maintained @ low pH 3-5 which is inhibitory to pathogens (2 sq meters) b. Mucous membranes i. All openings are lined w/ membrane (400 sq meters) ii. Saliva, tears, and mucous secretions act to wash away potential invaders and also contain antibacterial or antiviral substances 2. Physiological barriers a. Gastric acidity i. An innate physiologic barrier to infection b/c very few ingested microorganisms can survive the low pH of the stomach contents b. Soluble factors: i. Lysozyme 1. chews up cell walls of gram +; in tears 2. an enzyme present in tear, saliva, and mucous secretions that digests mucopeptides in bacterial cell walls and thus functions as a nonspecific antibacterial agent. It has frequently been used as a target antigen in immunological studies ii. complement proteins 1. a group of serum proteins that participates in an enzymatic cascade, ultimately generating the cytolytic membrane- attack complex iii. mannose-binding lectins iv. interferons 1. (IFNs) several glycoprotein cytokines produced and secreted by certain cells that induce an antiviral state in other cells and also help to regulate the immune response 3. Cell barriers a. Blood monocytes and tissue macrophages b. Dendritic cells i. Bone-marrow-derived cells that descend through the myeloid and lymphophoid lineages and are specialized for antigen presentation to helper T cells c. Neutrophils, eosinophils, and basophils i. Neutrophils a circulating, phagocytic granulocyte involved early in the inflammatory response. It expresses Fc receptors and can participate in antibody-dependent cell-mediated cytotoxicity. They are the most numerous white blood cells in the circulation ii. Eosinophils motile, somewhat phagocytic granulocytes that can migrate from blood to tissue spaces. They have large numbers of 2 IgE receptors and are highly granular. They are thought to play a role in the defense against parasitic organisms such as roundworms iii. Basophils a nonphagocytic granulocyte that expresses Fc receptors for IgE. Antigen-mediated cross-linkage of bound IgE induces degranulation of basophils d. N atural K iller cells i. A class of large granular cytotoxic lymphocytes that dont have T- or B-cell receptors. They are antibody-independent killers of tumor cells and also can participate in antibody-dependent cell-mediated cytotoxicity 4. Inflammatory barriers indication: pain, redness, heat, swelling - inflammatory responses to tissue damage and/or tissue invasion a. Vasodilation of capillaries (arteries) causes redness & heat b. Increase in capillary permeability gets water net out of the capillaries; swelling c. Phagocytosis causes the pain; squeeze to kill causing the pus to damage tissue; pain i. As phagocytic cells accumulate at the site and begin to phagocytose bacteria, they release lytic enzymes, which can damage nearby healthy cells. The accumulation of dead cells, damage nearby healthy cells.... View Full Document

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