EXPLAIN WHY INFLAMMATORY RESPONSE IS NOT VERY CRUCIAL TO A VIRAL INFECTION.

January 7th, 2009 Posted in noodtarareid.com | edit

THIS QUESTION IS ABOUT IMMUNOLOGY

Hello khai, To start, the inflammatory response is our body?s way to fight bacterial infection. The immune response is the body?s defense against viruses. Our body's defense system discerns the type of enemy trying to invade, and launches the appropriate response, be it inflammatory or an immune response. This site has a simple, yet explanatory animation on the inflammatory response. It?s a good basic way to understand the response. Notice the white cells, and neutrophils fighting bacteria. http://www.sumanasinc.com/webcontent/anisamples/dynamicillustrations/inflammatory.html Overall effects of the inflammatory response: ?Blood vessels in the infected area dilate, and as a result blood flow to the area increases. This makes skin in the area look red and feel warm. Capillaries in the area become more permeable allowing fluid to seep into the surrounding tissue. As this occurs oedematous swelling around the infected site occurs. The swelling and the effects of some of the chemicals released results in pain. Hence clinical characteristics of the inflammatory response are known as redness, heat, oedema and pain. http://www.jdaross.cwc.net/inflammatory_response.htm ?INFLAMMATION The inflammatory response (inflammation) occurs when tissues are injured by bacteria, trauma, toxins, heat, or any other cause. Chemicals including histamine, bradykinin, serotonin, and others are released by damaged tissue. These chemicals cause blood vessels to leak fluid into the tissues, resulting in swelling. This helps isolate the foreign substance from further contact with body tissues. The chemicals also attract white blood cells that "eat" microorganisms and dead or damaged cells. The process where these white blood cells surround, engulf, and destroy foreign substances is called phagocytosis, and the cells are collectively referred to as phagocytes. Phagocytes eventually die. Pus is formed from a collection of dead tissue, dead bacteria, and live and dead phagocytes.? http://www.nlm.nih.gov/medlineplus/ency/article/000821.htm Phagocytes are white blood cells, neutrophils usually, to be precise that destroy organisms. (Phage is of Greek origin, meaning to eat). http://www.nlm.nih.gov/medlineplus/ency/imagepages/9478.htm More phagocytosis http://www.whfreeman.com/immunology/CH01/phagocytosis.htm ?The functions of the inflammatory response include: 1) The delivery of effector molecules and cells to the sites of infection. 2) The formation of a physical barrier to the spread of the tissue damage or infection. 3) Wound healing and tissue repair. ?Phagocytic cells are the first major type of leucocytes to emigrate [first neutrophils, followed by macrophages] Neutrophils are short-lived cells which die within the tissues. Macrophages are much longer-lived. Later, lymphocytes (B and /or T) may also enter the site.? This is when they produce antibodies. http://bioweb.wku.edu/courses/biol328/Inflammation.htm A viral attack is much more complicated to describe. These illustrations help depict what happens: http://www.bio.davidson.edu/Courses/Immunology/Students/Spring2003/Ho/hostdefense2.jpg http://immuneweb.xxmc.edu.cn/immunology/virus-inf.gif ?Viruses invade living cells Although viruses can exist outside a host cell, they can't reproduce. Once inside a host cell, a virus either lays dormant for some time (lysogenic infection) or else starts reproducing immediately (lytic infection). The latter is more common. The tough outer coating of a lytic virus dissolves when inside the host cell. The virus then replicates its genetic material until the host cell is so full that it bursts. The released viruses then invade other host cells. The body's response to viral infection Viruses pose a considerable challenge to the body's immune system because they hide inside cells. This makes it difficult for antibodies to reach them. However, special immune system cells, called T-lymphocytes, can recognise and kill cells containing viruses, since the surface of infected cells is changed when the virus begins to multiply. Many viruses, when released from infected cells, will be effectively knocked out by antibodies, produced in response to infection or previous immunisation. Antibiotics kill bacteria by interfering with their metabolic processes, but viruses are so simple they use their host cells to perform their activities for them. This is why antibiotics are useless against viral infections. Antiviral drugs work by interfering with the viral enzymes. Antiviral drugs are currently only effective against a few viral diseases, such as influenza, herpes, hepatitis B and C and HIV, but research is ongoing. A naturally occurring protein, called interferon (which the body produces to help fight viral infections), can now be produced in the laboratory and is used to treat hepatitis C infections. Immunization against viral infection is not always possible: It is possible to vaccinate against many serious viral infections such as measles, mumps, hepatitis A and hepatitis B. An aggressive worldwide vaccination campaign, headed by the World Health Organization (WHO), managed to wipe out smallpox. However, some viruses - such as those that cause the common cold - are capable of mutating from one person to the next. This is how an infection with essentially the same virus can keep dodging the immune system. Similarly, vaccination for these kinds of viruses is difficult, because the viruses have already changed their format by the time vaccines are developed.? http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Infections_bacterial_and_viral?OpenDocument There are 2 immune response, humoral and cell mediated. ?humoral - defends the body against invading antigens through secretion of special proteins called antibodies 2.5.2. cell-mediated involves specialized cells attack antigens directly regulates activity of humoral system (26-4) 3.1. Are produced in the bone marrow (B-lymphocytes) and thymus (T-lymphocytes) 3.2. Circulate between the blood, tissue fluid, and lymph 3.3. B Lymphocytes (B-cells) mediate the humoral immune response 3.3.1. Has thousands of antibody molecules mounted in its cell membrane composed of heavy and light chains (26-5) binds to two specific antigen molecules (26-6) 3.3.2. Engulfs bound antigens and digests into smaller fragments 3.3.3. Stimulated B-cell (26-7) produces numerous plasma cells which are antibody factories which secret antibodies identical to those on the surface. these circulate freely in blood and lymph and attack antigens 3.3.4. Stimulated B-cell also produces memory cells which are lymphocytes like itself these remain in circulation for months and "remember" the antigen during future exposure. 3.3.5. Agglutination (clumping) of antibodies bound to antigens (26-8) easier for large phagocytic macrophages in lymph to recognize bound antigens (26-9) NK (natural killer) lymphocytes recognize bound antibodies, bind to them, and secrete powerful chemicals to destroy them bound antibodies trigger enzymatic reactions (complement cascade) the leads to cell lysis 3.4. T-Lymphocytes Control the Cell-Mediated Immune Response 3.4.1. T lymphocytes have T-cell receptors instead of antibodies on surface membrane 3.4.2. T-cell receptors (26-10) are not secreted but stick to lymphocyte recognize and bind to only one antigen molecule for recognition, antigen must be bound to special marker protein (major histocompatibility complex, MHC) and presented to the T-cell by a special antigen-presenting cell. 3.4.3. Two types of MHC proteins MHC-II - found on membranes of b cells, cytotoxic T cells and macrophages MHC-I - found on membranes of all other cells of the body Structure and function of MHC molecules (a) (26-11) (b) (26-12) (c) (26-13) 3.4.4. Summary of cell-mediated immune responce (26-14) Beta cells (26-15) T Cells (26-16) 3.4.5. Viral infection (26-17) antigens of virus attach to MCH-I proteins T-cells bind to antigen- MCH-I complex T-cells replicate producing memory T cells, Helper T-cells, Suppresser T cell, and Cytotoxic T-cells helper T-cells produce cytokines that activate other cells of the immune system (macrophages and other B and T cells); they also stimulate antigen bound B-Cells to divide and produce antibodies. suppresser T-cells inhibit activity of macrophages and other lymphocytes; they stop the immune response when no longer needed. cytotoxic T-cells search out abnormal cells (such as cancer cells or virus-infected cells) and destroy them http://www.agen.ufl.edu/~chyn/age2062/lect/lect_26/lect_26.htm ?If innate immune cells (dendritic cells) decide that the material is dangerous (part of a virus or bacteria), then they stimulate a specialized group of white blood cells causes CD4+ helper T cells to become activated. CD4+ refers to a surface protein on this class of T cells. Helper T cells can stimulate another group of white blood cells called B cells to produce antibodies that bind that specific antigen and immobilize it, preventing it from causing infection. Antibodies are specific for only one antigen. B cells must interact with Helper T cells, other specialized white blood cells, to initiate antibody production. An important concept is that once activated, memory cells are produced that insure that a more rapid and stronger immune response can be made upon re-exposure to the same pathogen. This is why vaccinations provide lasting protection against disease. Memory helper T cells are labeled CD4+ CCR5+, to note that the chemokine receptor (CCR5) is present on the surface of the helper T cell. These cells migrate and reside in the mucus membranes of our body.? http://www.biology.arizona.edu/immunology/tutorials/AIDS/response.html ?The leukocytes circulate through the body between the organs and nodes by means of the lymphatic (pronounced: lim-fah-tik) vessels. (You can think of the lymphatic vessels as a type of highway between the rest stops that are the lymphoid organs and lymph nodes). Leukocytes can also circulate through the blood vessels. In this way, the immune system works in a coordinated manner to monitor the body for substances that might cause problems. There are two basic types of leukocytes: The phagocytes (pronounced: fah-guh-sytes) are cells that chew up invading organisms. The lymphocytes (pronounced: lim-fuh-sytes) are cells that allow the body to remember and recognize previous invaders. There are a number of different cells that are considered phagocytes. The most common type is the neutrophil (pronounced: noo-truh-fil). Neutrophils primarily fight bacteria. So when doctors are worried about a bacterial infection, sometimes they order a blood test to see if a patient has an increased number of neutrophils triggered by the infection. Other types of phagocytes have their own jobs to make sure that the body responds appropriately to a specific type of invader. There are two kinds of lymphocytes: the B lymphocytes and the T lymphocytes. Lymphocytes start out in the bone marrow and either stay there and mature into B cells, or they leave for the thymus gland, where they mature into T cells. B lymphocytes and T lymphocytes have separate jobs to do: B lymphocytes are like the body's military intelligence system, seeking out their targets and sending defenses to lock onto them. T cells are like the soldiers, destroying the invaders that the intelligence system has identified.? There are a lot of simplified explanations on this page. Keep reading! http://kidshealth.org/parent/general/body_basics/immune.html ?These white blood cells are very important for fighting infection. They are good at fighting bacteria and fungal infections. They can Move to sites of infection in the body Stick to invading bacteria or fungi Swallow up the invader Kill the bacteria they have swallowed with chemicals B cells and T cells The white blood cells involved in the acquired immune response are called 'lymphocytes'. There are two main types of lymphocytes - B cells and T cells. B and T lymphocytes are made in the bone marrow, like the other blood cells. They have to fully mature before they can help in the immune response. B cells mature in the bone marrow. But the immature T cells travel through the blood stream to the thymus gland where they become fully developed. Once they are fully mature, the B and T cells travel to the spleen and nodes ready to fight infection. What do B cells do? B cells react against invading bacteria or viruses by making proteins called antibodies. The antibody made is different for each different bug. The antibody locks onto the surface of the invading bacteria or virus. The invader is then marked with the antibody so that the body knows it is dangerous and it can be killed off. The B cells are part of the memory of the immune system. The next time the same bug tries to invade, the B cells that make the right antibody are ready for it. They are able to make their antibody more quickly than the first time the bug invaded. http://www.cancerhelp.org.uk/help/default.asp?page=118#neut ?The Normal Immune System Response. The inflammatory process is a byproduct of the body's immune system, which fights infection and heals wounds and injuries: When an injury or an infection occurs, white blood cells are mobilized to rid the body of any foreign invaders, such as bacteria or viruses. The masses of blood cells that gather at the injured or infected site produce factors to repair wounds, clot the blood, and fight any infective agents. In the process, the surrounding area becomes inflamed and some healthy tissue is injured. Under normal conditions, the immune system has other factors that control and limit this inflammatory process.? ?Lymphocytes include two subtypes known as T-cells and B-cells. Both types of cells are designed to recognize foreign substances (antigens) and to launch an offensive or defensive action against them: B-cells produce antibodies, which are designed to attack the antigens. Antibodies can either ride along with a B-cell or travel on their own. T-cells have special receptors attached to their surface that recognize the specific antigen. T-cells are further categorized as killer T-cells or helper T-cells (TH cells). Killer T-cells directly attack antigens found on bacteria or other cells. Helper T-cells also recognize antigens, but their role is two fold. They stimulate B-cells and other white cells to attack the antigen. They also produce cytokines, powerful immune factors that have an important role in the inflammatory process. Helper T-Cells, Cytokines, and the Inflammatory Response. The actions of the helper T-cells (TH cells) are of special interest. Researchers have observed high numbers of TH cells in psoriatic plaques: The activated TH cells infiltrate the skin cells in psoriasis and, in the case of psoriatic arthritis, also the joints. (There has been some debate over whether psoriatic arthritis is a unique disorder, but evidence now suggests that both psoriatic arthritis and psoriasis are caused by the same faulty immune process.) TH cells normally stimulate B-cells to produce antibodies. In the case of psoriasis, however, they appear to direct the B-cells to produce autoantibodies (self antibodies), which are directed against the body's own cells. In the case of psoriasis, they target self antigens in skin cells; in psoriatic arthritis, cells in the joints also come under attack. In the resulting autoimmune process, autoantibodies remain in circulation and continue to mount an immune attack against these cells.? http://adam.about.com/reports/000087_1.htm The Lymphatic System The three primary functions are: ?To collect and return interstitial fluid, including plasma protein to the blood, and thus help maintain fluid balance, To defend the body against disease by producing lymphocytes, To absorb lipids from the intestine and transport them to the blood. http://www.jdaross.cwc.net/lymphatic_system.htm More information on the immune system ====================================== http://en.wikipedia.org/wiki/Immune_system http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CMI.html http://www.factmonster.com/ce6/sci/A0861814.html http://www.newton.dep.anl.gov/askasci/bio99/bio99508.htm http://facultyresearch.bwh.harvard.edu/cgi-bin/search.cgi?id=40&kw= http://www.tulane.edu/~dmsander/WWW/MBChB/8a.html Hope this answers your questions! Please ask for an Answer Clarification, before rating, if any part of my answer is unclear. Regards, Crabcakes Search Terms ============= antigenic viral response inflammatory response bacteria + inflammatory response viral response immunity

This seems to me to be a strange statement. Inflammation is one of the crucial ways in which the body handles infection -- be it viral, bacterial, or other. The purpose of the inflammatory response, in general, is to attract effector cells (e.g. neutrophils, macrophages, T cells) and molecules (e.g. antibodies) to the site of infection. What is inflammation, really? It is the body's way of letting white blood cells leave the blood vessels to enter infected tissues. Infected cells release chemical signals (i.e. cytokines such as TNF-a, IL-1) to cause changes to the endothelial cells of blood vessels. These changes include increased levels of adhesion molecules (e.g. ICAM, selectin) on the interior of the blood vessels that increase permeability of cells. The swelling that you get during inflammation is simply plasma (the water component of blood) leaving the blood vessels along with the white blood cells due to increased permeability of the vessels. I'm not sure why somebody gave you the impression that inflammatory responses are not crucial for a viral infection. When you have a cold, for example, you get a sore throat -- which is just inflammation. That inflammatory response is crucial for your body to eliminate the cold viruses!

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EXPLAIN WHY INFLAMMATORY RESPONSE IS NOT VERY CRUCIAL TO A VIRAL INFECTION.

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