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UM BIOM 250N - Autoimmune Disease and Viruses
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BIOM 250 1st Edition Lecture 22Outline of Last Lecture I. Immunologic-based TestsII. Hypersensitivity ReactionsOutline of Current Lecture I. Cytotoxic ReactionsII. Cell-Mediated ReactionsIII. Autoimmune DiseaseIV. VirusCurrent LectureBonus Question (will be on next exam) In the mechanism for anaphylaxis, when you have IgE antibodies on a basophil and they become cross-linked by antigen the cell will: degranulate.I. Cytotoxic Reactionsa. Involve activation of complement by IgG or IgM bound to an antigenic celli. Can be foreign cell or host cell with foreign antigen on its surfaceb. Ex: transfusion reactionsII. Cell-Mediated Reactionsa. Delayed type hypersensitivitiesi. Cell-mediated mainly by T cellsii. Usually requires a day or more to become apparentiii. Time required for T cells and macrophages to migrate to site of foreign antigenb. To begin, sensitization by antigen binding to tissue cellsi. Macrophages phagocytize and present to T cellsii. First exposure no reaction but many T cells and memory T cells producediii. Second exposure, many T cells then attack self-cells with antigen on surfaceIII. Autoimmune Diseasesa. During fetal development T cells that can recognize and attack self cells are deletedThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.i. This gives the immune system self-toleranceb. Autoimmunity is loss of self-tolerancei. Now immune system attacks own cellsc. Ex: multiple sclerosisi. T cells and macrophages attack the myelin sheath on nervesii. Causes fatigue, weakness, nerve paralysisiii. Most common in white women living in northern latitudesiv. May have a viral component; viral infection may produce antigen with structure similar to myelin proteind. Immune system and cancer:i. Cancer cells usually have many mutations that cause them to proliferate without the normal cell or tissue controls1. This will produce tumor-associated antigens on the cell surfaceii. Cancer cells can then be detected by immune surveillance1. Attacked/lysed by CTLs or macrophagesiii. As you age, immune surveillance weakense. Immunotherapy for cancer:i. So if cancer can be cells with a non-self or foreign antigen then why can we not vaccinate against it?1. Still under developmentii. However vaccines can be used to prevent some cancers1. Ex: cervical cancer—HPV vaccineIV. Virusa. Virus: obligatory intracellular parasitei. Outside of a cell a virus has no metabolismii. Must enter a living cell to reproduceiii. Takes over the cell functions to produce structural proteins, enzymes, andcopies of its nucleic acidb. Viruses contain only one type of nucleic acidi. They are either DNA or RNA virusesc. Viruses have a protein coat enclosing the nucleic acidi. The protein coat can be naked (protein only)ii. Can have an envelope derived from the host membraneiii. May also have spikes, carb/protein structures projecting outiv. Spikes can be used to attach to host cells/cell receptorsd. Viruses have a host range—species specifici. Can usually only infect a specific cell type from one speciesii. Some viruses can cross the species barriere. Virus sizesi. Rough estimate is that human viruses range from 20nm to several hundredf. Multiplication of animal viruses:i. Attachment: virus attaches to cell membraneii. Penetration: by receptor-mediated endocytosis or fusion of viral envelopewith cell membraneiii. Biosynthesis: production of nucleic acid and proteinsiv. Maturation (assembly): nucleic acid and capsid proteins assemblev. Release: by budding (enveloped viruses) or rupture1. Enveloped viruses are susceptible to some treatments that do not effect naked virusesg. DNA Oncogenic viruses:i. If a cells DNA is altered or mutated then it can become cancerous1. Cancer begins when a cell loses its ability to control its growth2. This happens when certain genes are activated improperly or inactivated3. Virus can integrate its DNA into the host cell’s chromosome4. Can cause activation or inactivation of genesii. ex: human papilloma virus (HPV)1. Almost all cervical and anal cancers are caused by HPVh. Latent viral infections:i. All human herpes viruses remain in host cells throughout the life of the individual1. Herpes simplex virus produces cold sores2. Chicken pox virus can enter nerve cells and stay latent for lifea. Aging or immunosuppression can allow reactivation and this causes


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