This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: Introductory Lecture: Millions of different antibodies can be made, and would require 4-5 billion nucleotides if recombination did not occur. Disorders of the immune system affect 10-20% of the US population and are the third leading cause of morbidity/mortality here. 80% of childhood cancers arise in immune cells. Lecture 1: Innate Immunity Innate immunity: Pre-existing mechanisms always ready for a rapid, stereotyped first line of defense. It uses germline encoded receptors to recognize general pathogen patterns. All innate cells of the same type have the same receptors. It kills pathogens and also activates the adaptive immune response. It suppresses infection of pathogens (often rapidly dividing) with moderate efficacy for a few days until adaptive immunity is activated. Adaptive immunity: Requires several days to a week to be activated. It is a specific, learned response to a precise molecular structure. It uses gene rearrangement to generate its receptors, and specific cells proliferate through clonal expansion. Adaptive immunity is responsible for immune memory. The innate immune system appeared early in evolution (sponges) than did the adaptive immune system (sharks). Part of innate immunity are the bodys barriers. They include epithelial layers, mucus to prevent adhesion time, and antimicrobial peptides. These peptides include -defensins produced by neutrophils, -defensins produced by epithelial cells and histatins (in saliva). The effector mechanisms of the innate immune system include recruitment (inflammation and acute phase response), opsonization, phagocytosis, intracellular killing and cytokine secretion. Bacteria attempt to evade these, and they have limited effectiveness against viruses. Neutrophils make up 50-70% of WBCs, lymphocytes 20-35%, monocytes 3-7%, eosinophils 1-3%, and basophils 1%. Neutrophils and macrophages are the most important phagocytic cells. Both are derived from pluripotent hematopoietic stem cells and a further differentiated myeloid progenitor cell (granulocyte-monocyte colony forming cell). They generally use the same mechanisms, but neutrophils live about a day, are activated in acute inflammation, and destroy only bacteria using reactive oxygen species. Macrophages, in contrast, live weeks, act in chronic inflammation, attack many microorganisms, present antigen, secrete lots of cytokines, and use NO as well as reactive oxygen. Neutrophils job is to phagocytose foreign stuff. They are abundant in the circulation and tissues, and theyre very mobile. Because of this, theyre usually the first to respond. The granules in neutrophils are azurophilic, and contain hydrolytic enzymes, defensins, and myeloperoxidase for killing stuff. Other granules carry receptors for complement, adhesion, and cytokines and are ready to be exocytosed with the appropriate signal. Immature neutrophils dont yet have the characteristic nuclei of polymorphonuclear cells (mature neutrophils), rather they are banded. Immature neutrophils dont yet have the characteristic nuclei of polymorphonuclear cells (mature neutrophils), rather they are banded....
View Full Document
This note was uploaded on 02/08/2012 for the course PATHOLOGY 3245 taught by Professor X during the Spring '11 term at UWO.
- Spring '11