Chapter 19: DISORDERS ASSOCIATED WITH THE IMMUNE SYSTEM Flashcards
Hypersensitivity reactions
-Allergies
-Exaggerated immune response leading to damage
-After sensitized to the allergen
-Immunological responses to antigens (allergens) leading to tissue damage rather than immunity
-Occur when a person has been sentitized by previous exposure to an antigen
Type I anaphylactic reaction
-Initial exposure- no reaction
-Occur w/in 2-30 min after a person becomes sensitized to an antigen w/ repeated exposure
Mechanism of anaphylaxis
-Involves B cells and IgE antibodies made in response to allergen
-Sensitizations: IgE antibodies produced in response to an antigen bind to Fc receptors on mast cells and basophils
-Upon later exposure to the antigen, IgE/Fc receptors are cross-linked by an antigen, triggering degranulation and the release of histamine and other mediators
-Degranulated mast cells that has reacted w/ an antigen and released granules of histamines and other reactive mediators
Type I (anaphylactic) immediacy reactions
-IgE antibodies, produced in response to an antigen, bind to mast cells and basophils
-Degranulated mast or basophil cells release histamines and other mediators
Leukotrienes
-chemical mediator
-constriction of bronchioles
Prostaglandins
-chemical mediator
-dilated blood vessels
-itching
-constricted bronchioles- wheezing and difficulty breathing
Histamines
-chemical mediator
-excessive mucus and glandular secretions
Systemic anaphylaxis
-Allergen ingested or injected
-Release of mediators result in drop in BP (shock)
-Fatal w/in a few min
-Treatment- Epinephrine
Localized anaphylaxis: hives
-Urticaria (hives)
-Characterized by the wheal (fluid-itchy swelling) surrounded by a flare (reddening)
Localized anaphylaxis: hay fever
-Seasonal reaction to inhaled plant pollen or mold spores
-Ex. Aspergillosis
Localized anaphylaxis: asthma
Episodes of impaired breathing due to severe bronchoconstriction
Localized anaphylaxis: eczema
-Atopic dermatitis
-Food allergies
Prevention of anaphylaxis
-Skin testing
-Identify allergen
-Desensitization
-IgG blocking antibody
Treatment for Type I hypersensitivities
-Environmental intervention- avoid allergens
-Drug intervention
-Antihistamines
-Epinephrine- systemic anaphylaxis
-Steroids (flonase, Advair, etc.)
-Singulair
Type IV (Delayed Cell-mediated) Reactions
-Due to T cell proliferation
-Sensitized T cells secrete cytokines that attract macrophages
-Allergic contact dermatitis- rash, itching
-Haptens combine w/ proteins in skin
-Ex. latex, poison ivy, cosmetics, and nickel in jewelry
-Dx: patch test- keep patch on for 2 days
-Delayed reaction
Allergic Contact Dermatitis: Type IV hypersensitivity
-Primary contact: no dermatitis
-Secondary contact: dermatitis
Tuberculin skin test: Type IV hypersensitivity
-Purified protein derivative of M tuberculosis
-Inj into dermis of skin
-Read at 48hrs
-More than 10mm- (+)
-Followed up by chest x-ray
-When (+) T cell hypersensitivity response
Immunotherapy
-Immunotoxins link poisons w/ a monoclonal antibody
-TNF, IL-2, and INFs may be useful in treating cancer
-Desensitization (IgG Blocking Antibody) for Type I Hypersensitivities
-making use of the immune system to attack tumor cells, either by enhancing the normal immune response or by using toxin-bearing specific antibodies
-Immunotoxins are chemical poisons linked to a monoclonal antibody; the antibody selectively locates the cancer cell for release of the poison.
-Cytokines: Tumor Necrosis Factor, Interleukin-2, and Interferons may be useful in treating cancer and diseases.
-IgG Blocking Antibody for Immediate Hypersensitivity Reactions
-Circumventing the Allergic Attack
Describe the mechanism of Type I hypersensitivity and the process of desensitization.
Type I hypersensitivity, or immediate hypersensitivity, is an allergic reaction mediated by IgE antibodies. It involves a sensitization phase where allergens trigger IgE production and attachment to mast cells and basophils. Upon subsequent exposure, the allergen cross-links IgE on these cells, leading to their degranulation and release of inflammatory mediators, causing symptoms like hives, sneezing, and bronchoconstriction. Desensitization, a treatment for Type I hypersensitivity, involves slowly increasing allergen exposure to stimulate the production of blocking antibodies (IgG and IgA) that bind to and neutralize the allergen, reducing its ability to bind to cell-bound IgE and trigger a reaction.
-ex. Cancer vaccines, checkpoint inhibitors, adoptive cell transfer therapies
Describe the mechanism of Type IV hypersensitivity (cell-mediated reactions) and name two examples.
Type IV hypersensitivity, also known as cell-mediated hypersensitivity or delayed-type hypersensitivity, is an immune response where T cells, rather than antibodies, mediate tissue damage. This delayed reaction (24-72 hours after antigen exposure) is characterized by the recruitment and activation of immune cells like macrophages, leading to inflammation and tissue damage. Two examples of Type IV hypersensitivity are contact dermatitis (like poison ivy) and the tuberculin skin test.
Describe the structure and replication of the human immunodeficiency virus (HIV).
HIV is a retrovirus with a complex life cycle. It’s structured with a core containing two RNA strands, surrounded by a capsid, a matrix, and an outer envelope studded with glycoproteins. Replication involves binding to CD4 cells, reverse transcription of RNA to DNA, integration into the host genome, transcription of viral RNA, and the production of new viral particles that bud from the host cell.
Discuss the transmission, diagnosis, treatment, and prevention of HIV infection.
HIV, the virus that causes AIDS, is primarily transmitted through unprotected sexual contact, shared needles or syringes, and from mother to child during pregnancy, childbirth, or breastfeeding. Diagnosis involves blood or saliva tests that detect HIV antibodies or the virus itself. Treatment, called antiretroviral therapy (ART), significantly reduces the viral load and prevents transmission, allowing people with HIV to live long and healthy lives. Prevention involves condom use, PrEP (pre-exposure prophylaxis), treatment as prevention (TasP), and avoiding risky behaviors.
