HLTH 201: Ch. 12 - Disorders of the Immune Response

what is a hypersensitivity reaction?

abnormal immune response to a normally harmless substance/antigen

what are the types of hypersensitivity reactions?

Type I: allergic reaction, Type II: cytotoxic hypersensitivity, Type III: immune complex hypersensitivity, Type IV: cell-mediated delayed hypersensitivity

What is a type I hypersensitivity reaction?

upon first exposure to the antigen, IgE antibodies are made instead of IgG. IgE antibodies attach to mast cells and when host is re-exposed to the allergen, allergen attaches to IgE antibody causing the mast cell to release histamine

what occurs during the early response of the inflammatory response?

vasodilation

what occurs during the late response of the inflammatory response?

mucosa edema, mucus secretion, bronchospasm, epithelial damage, WBC infiltration

what type of hypersensitivity reaction is asthma?

Type I

what occurs during the primary/immediate phase of asthma?

histamine release causing vasodilation, vascular leakage, smooth muscle constriction

what occurs during the secondary/late phase of asthma?

tissues infiltrate with eosinophils, tissue destruction

What is anaphylactic shock?

extreme type I sensitivity reaction

what occurs during anaphylaxis shock?

degranulation of many mast cells causing dilation of the vascular system

what are the signs and symptoms for anaphylaxis shock?

sudden vasodilation causing large drop in BP, histamine irritates nerve endings causing hives, increase mucus production, bronchoconstriction, erythema, vomiting, abdominal cramping

what is the emergency treatment for anaphylaxis shock?

administer epinephrine

What does epinephrine do?

causes vasoconstriction, increases rate and strength of heartbeat, relaxes smooth muscle in bronchioles

What is type II hypersensitivity reaction?

antibody mediated hypersensitivity reaction

what occurs during a type II hypersensitivity reaction?

antibodies interact with tissue and cause tissue destruction

what are the causes of type II hypersensitivity reactions?

transfusion reactions, drug reactions

what are the 3 types of type II hypersensitivity reactions?

compliment and antibody mediated cell destruction, compliment and antibody mediated inflammation, antibody mediated cellular destruction

what are examples of type II reactions: compliment and antibody mediated cell destruction?

blood transfusion incompatibility, drug reaction: hemolytic anemia

what are examples of type II reactions: compliment and antibody mediated inflammation?

organ transplant reaction (antibodies deposit on extracellular tissue causing damage and inflammation), Goodpasture syndrome

what are examples of type II reactions: antibody mediated cellular destruction?

graves diseases (antibody attaches to receptor to activate cell), myasthenia gravis (antibody binds to receptor to destroy cell)

What is a type III hypersensitivity reaction?

immune complex reactions: antigen and antibody complex

how are type III hypersensitivity reactions caused?

antigen and antibody complex infiltrate the walls of blood vessels causing inflammation and damage to blood vessels

what are examples of systemic type III hypersensitivity reactions?

autoimmune vasculitis (inflammation of vasculature), glomerulonephritis (inflammation of glomeruli in kidneys)

what are examples of local type III hypersensitivity reactions?

arthus reaction (localized tissue necrosis)

what is a type IV hypersensitivity reaction?

cell mediated reactions causing cytotoxic T cells to attack antigens

what are the types of Type IV hypersensitivity reactions?

direct cell mediated cytotoxicity, delayed type hypersensitivity

what is a direct cell mediated cytotoxicity type IV hypersensitivity reaction?

cytotoxic T cells directly kill antigen containing cells (kills viral infected cells)

what are examples of delayed-type IV hypersensitivity reaction?

TB testing, contact dermatitis, type I diabetes

What is an allograft?

tissue/organ transplant between the same species

What is isograft?

tissue/organ transplant between identical twins

what is an autograft?

tissue/organ transplant from one part of the body to another

what is a xenograft?

tissue/organ transplant between different species

what are the types of host vs graft rejections?

hyperacute rejection, acute rejection, chronic/late rejection

what is a hyperacute rejection?

rejection that occurs once blood flow is established to the organ (immediately) due to host having pre-existing antibodies against the organ

what is an acute rejection?

rejection that occurs several weeks after transplantation

what is a chronic/late rejection?

rejection occurs several months to years after transplantation

What is graft vs host disease?

transplanted organ attacks the host tissue

what must occur in order for a patient to have graft vs host disease?

the perfect storm

what is the perfect storm (graft vs host disease)?

transplant must have functional immune cells, recipient must have antigens foreign to donors T-lymphocytes, recipient has to be immunocompromised

what are ways to prevent transplant rejection?

matching human leukocyte antigen (HLA) and major histocompatibility complex (MHC), using immunosuppressant drugs (if HLA.MHC dont match)

what are autoimmune diseases?

body begins attacking its own tissues by making antibodies against the tissues

What is immunodeficiency?

loss of part or all the function of the immune system

what are primary immunodeficiencies?

genetic or congenital disorders

what are secondary/acquired immunodeficiencies?

malnutrition, immunosuppressant drugs, AIDS, kidney disease, Hodgkin's lymphoma, chemotherapy (suppresses immune system because WBCS are nonfunctional)

what are opportunistic infections?

infections that a person with a functional immune system would not develop

what are treatments of immunodeficiency?

antibody replacement, bone marrow/thymus transplant (T cells mature in thymus)

How is HIV transmitted?

body fluids: sexual contact, breast milk, blood to blood contact (contaminated needles, transfusions, during pregnancy or birth)

what is the clinical course of HIV infection?

primary infection phase, latency phase, overt AIDS phase

what occurs during the primary infection phase of HIV infection?

signs of systemic infection occur (flu like s/s)

what occurs during the latency phase of HIV infection?

virus begins replicating and T helper cell count gradually falls

how long does the latency phase of HIV infection last?

about 10 years

what is the normal level for T helper cells?

500-1,500 cells/mm3

what occurs during the overt AIDS phase of HIV infection?

T helper cell count falls below 200 cells/mm3

What is AIDS?

acquired immune deficiency syndrome

what are examples of AIDS associated illnesses?

opportunistic infections, malignancies, wasting syndrome, metabolic disorders

what are opportunistic infections that can be caused by AIDS?

respiratory, gastrointestinal, nervous system

what malignancies can be caused by AIDS?

kaposi sarcoma, non-hodgkins lymphoma

What is wasting syndrome?

weight loss of \>10% of starting weight