Hypersensitivities Flashcards

Question

what treatment is available for allergies?

Answer 1

there is no real treatment to completely eliminate allergies 1) identify and avoid the allergen 2) immunotherapy = therapeutic anti-IgE antibody 3) antihistamines = bind to histamine receptor and block downstream effects 4) adrenalin = reverse systemic anaphylaxis 5) anti-inflammatory drugs

Answer 2

the intial step towards an allergy is an allergen crossing an epithelial barrier, often through skin (i.e touch peanut butter) 1) sensitization (first exposure @ skin) - the epithelial barrier loses integrity, allowing peanut allergens to enter. - epithelial cells release cytokines: TSLP, IL-33, and IL-25. - these cytokines activate dendritic cells (DCs), which take up the peanut allergens, process them, and present them on MHC Class II molecules. - the dendritic cells migrate to secondary lymphoid tissue (e.g., lymph nodes), where they present peanut allergen peptides to CD4+ T cells. - the dendritic cells also release polarizing cytokines to cause differentiation of CD4+ T cells into TH2 cells. - TH2 cells then activate B cells with matching BCRs, leading to the production of IgE antibodies through class switching 2) second exposure (ingestion) - intestinal epithelial cells response to allergen by producing TSLP, IL-25 and IL-33 - these cytokines activate dendritic cells, TH9 cells, and innate lymphoid cells (ILCs). --> dendritic cells present the peanut allergen to TH2 and TH9 cells. --> TH9 cells secrete IL-9, which helps support and activate mast cells. --> ILC2 cells release IL-5 and IL-13, which recruit and activate basophils and eosinophils. - TH2 cells activate B cells, making more plasma cells that produce IgE antibodies - granulocytes release active mediators (i.e histamie) that causes food allergy symptoms

Answer 3

- early introduction of allergens (such as peanuts) can help establish immune tolerance, reducing the likelihood of developing allergies later in life. - intervention is more effective when it occurs earlier in life rather than later, as it can help prevent the immune system from becoming sensitized to allergens in the first place.

Answer 4

Yes, sensitization is required for an individual to develop an allergy. - sensitization occurs occurs when the immune system first encounters an allergen and produces IgE antibodies - on subsequent exposures, these antibodies trigger an allergic reaction, causing symptoms like swelling, itching, or more severe responses.

Answer 5

A therapeutic protocol where an individual is repeatedly exposed to increasing amounts of allergen over time to build tolerance to the antigen - can be administered via injections, skin application, sublingual tablets, or even oral ingestion. - initially used for environmental allergies like pollen, dust, and mold. - while injections were traditionally used, desensitization can now be done with pills or sublingual treatments for convenience and reduced side effects.

Answer 6

a new treatment approach specifically designed for food allergies, especially for children with anaphylactic reactions - begins with very small doses of the allergen, typically in a hospital or doctor's office for safety. - doses are gradually increased over time. --> in high-risk patients, omalizumab (a monoclonal antibody) can be added = blocks IgE binding to mast cell FcεRs, reducing the risk of anaphylaxis during treatment

Answer 7

in a normal allergic response: - TH2 CD4+ T cells are activated and triggering class switching of B cells to produce plasma cells secreting IgE - The IgE binds to mast cells, which causes degranulation and an allergic reaction in OIT approach: - Low doses of allergen in OIT shift the immune response towards a TH1 dominance - TH1 CD4+ T cells support class switching to IgG4, which: 1) Binds to FcɣRIIB on mast cells, an inhibitory receptor that blocks mast cell degranulation. 2) competes with IgE for allergen binding - regulatory T cells (Tregs) are also activated, to actively suppress TH2 responses at low doses. - as doses increase, TH2 cells may undergo apoptosis (cell death) or become anergic (unresponsive). --> There is a threshold where the immune system becomes more tolerant to the allergen, reducing the allergic response over time.

Answer 8

- blood transfusion reactions - hemolytic anemias in newborns

Answer 9

tolerance is what our body learns to ignore or not ignore --> the ability of the immune system to differentiate between "self" and "non-self" --> determines what the body ignores (self antigens) or attacks (foreign antigens form pathogen or mismatched blood types)

Answer 10

blood types are determined by the presence or absence of certain antigens (sugars) on the surface of red blood cells - blood types are A, B, AB or O --> everyone has H antigen --> some also have A antigen or B antigen or BOTH - different sugar conformations determine whether an A antigen, B antigen, or both are produced, driving blood type diversity. *different sugar conformations are what dictate if a A antigen is made versus a B antigen etc*

Answer 11

- many microbes in the environment also express sugar antigens (A, B, H) that resemble those found on human cells - tolerance to certain pathogens is based on the antigens expressed on your cells - the absence of certain antigens leads to the production of antibodies against those antigens. tolerance mechanism: - If you express A and H antigens, your B cells recognize A and H as "self" and become tolerant --> you will produce anti-B antibodies = react to B - If you express B and H antigens, your B cells recognize B and H as "self." --> you will produce anti-A antibodies = react to A blood - if you express A, B, and H antigens, your B cells tolerate all three --> you can accept blood from from anyone = no recation - If you only have the H antigen, your B cells tolerate H but will respond to A and B antigen --> you produce anti-A and anti-B antibodies = react to A and B --> universal donor (everyone has H antigen) *essentially, whatever antigen you DON'T have, you have antibodies against them so if you're exposed to other antigen = reaction

Answer 12

- blood must be cross-matched prior to transfusion to avoid severe transfusion reactions - you have to make sure that the recipient doesn't have pre-existing antibodies agains the donors RBC antigens - if you dont, the pre-existing antibodies will bind to the donor RBC = bad

Answer 13

mechanism of reaction: - the recipient’s immune system may have IgM antibodies targeting donor RBC antigens (e.g., anti-A or anti-B antibodies). - these antibodies bind to antigens on donor RBCs. - the classical complement pathway is triggered leading to the formation of the Membrane Attack Complex (MAC). - RBCs are lysed by the MAC, releasing hemoglobin into the bloodstream. - released hemoglobin is filtered by the kidneys, which can lead to kidney damage. - hemoglobin is degraded into bilirubin, a by-product that, in high amounts, can be toxic and result in jaundice (yellowing of the skin and eyes).

Answer 14

- Type O blood is the universal donor, as it lacks A and B antigens, minimizing the likelihood of a reaction. - Type AB blood is the universal acceptor, as individuals with this blood type have no isohemagglutinins, making them tolerant to A and B antigens.

Answer 15

- a condition where IgG antibodies from the mother cross the placenta, targeting fetal red blood cells (RBCs) and leading to their destruction (hemolysis). - it occurs when there is incompatibility between the mother’s and fetus's Rhesus (Rh) blood group. - the mother would be Rh- and the fetus is Rh+ (inherited from the father) this only matters if theres a MISMATCH of Rh- and Rh+ between fetus/mother

Answer 16

1) first pregnancy = sensitization phase - normally, the maternal and fetal blood are separated by the placenta (no direct blood flo) - small amounts of fetal RBC crossing the placenta do not trigger an immune response initially because are mothers naive b-cells are not activated at threshold - during delivery, the placenta detaches from the uterine wall, causing fetal umbilical blood (Rh+) to enter the mothers blood circulation - the mothers immune system recognizes Rh+ blood as non-self and mounts an immune response - the mother produces IgM antibodies that destroy fetal RBC (do not cross placenta) - memory B-cells are created and class-switch to produce IgG antibodies for future responses 2) second pregnancy = immune response - small of amounts of fetal RBC cross the placeneta during a subsequent pregnancy, which is enough to activate the mothers memory b-cells from the past pregnancy - memory b-cells rapidly produce IgG antibodies which are small enough to cross placental barrier and attack fetal RBCs in the fetus (Rh+) - this causes anemia, and hemoglobin to breakdown = bilirubin accumulating = jaundice

Answer 17

the main treatment is to administer anti-Rh antibodies to the mother to prevent the initial sensitization event in first pregnancy - RhoGAM binds to fetal Rh+ RBCs that have entered the mother's circulation. - coated fetal RBCs are cleared by the maternal immune system before they can be recognized by B cells. - this prevents the mother's immune system from mounting a response or producing memory B cells, ensuring subsequent pregnancies are safe. *mothers are routinely tested for Rh compatibility and rising levels of maternal anti-Rh antibodies = indicated immune reaction against fetus RBCs*

Answer 18

it is also called delayed type hypersensitivity (DTH) - the only hypersensitivity reaction mediated by T cells rather than antibodies. - it involves a delayed response (1-2 days) as T cells recruit and activate macrophages - t-cells trigger excessive macrophage activation leading to tissue damage - typically caused by intracellular pathogens and contact antigens (skin exposure)

Answer 19

delayed type hypersensitivity requires an initial sensitization event by an antigen 1) first event: - APCs (dendritic, macrophages) present antigens (i.e poison ivy) that activate CD4+ TH1 cells and others 2) second event: - upon re-exposure, sensitized T cells release cytokines and chemokines. - this recruits and activates macrophages to the site of exposure. - the peak response takes 48-72 hours, allowing time for the Th1 cells to activate and recruit macrophages, resulting in a slow building concentration gradient at the exposure site.

Answer 20

a test to see if a person has been infected with tuberculosis or has had the vaccine - PPD from tuberculosis is injected into the skin - 2-3 days later, redness and swelling are check for at the injection site - if present, it indicates that memory T cells are recruiting macrophages, causing inflammation, and confirming a previous exposure to M. tuberculosis - if not present, it suggests that the person has not been previously been exposed to tuberculosis

Hypersensitivities Flashcards

(44 cards)