Microbio Week 6 (Exam 2) Flashcards
Which of the following factors is the first to be secreted upon mast cell activation?
Leukotriene C4
Prostaglandin D2
Histamine
IL-5
Acid cationic factor
Histamine
What is stored into granules and released immediately when mast cells are activated and degranulate?
Histamine
Penicillin cannot elicit an immune response on its own, but can elicit an immune response if coupled to a carrier protein. It is then referred to as a:
Antigen
Immunogen
Antibody
Hapten
Immunoglobulin
Hapten
Small molecules that cannot elicit an immune response themselves, but can when coupled to a protein
Haptens
Which of the following causes of cancer has been responsible for the very large increase in oral cancers over the last 10+ years?
HIV infection
HPV infection
Exposure to radiation
Exposure to chemical carcinogens
P. gingivalis infection
HPV infection
T/F: Tumors can evade the immune response.
True
Despite its vital protective role against pathogens, the immune system is often responsible for __________ __________ and is involved in the ___________ of many diseases
tissue injury; pathogenesis
A set of undesirable reactions by the normal immune system that require a “pre-sensitized” (immune) state
Hypersensitivities
What are the 4 types of hypersensitivities based on the triggering mechanism?
Immediate - Type I
Antibody-mediated - Type II
Immune complex-mediated - Type III
Cell-mediated - Type IV
Which type of hypersensitivity?
Cross-linking of IgE antibodies bound to mast cells by antigen (allergen)
Immediate - Type I
Which type of hypersensitivity?
Binding of IgG or IgM antibodies to antigens present on cells or basement membranes
Antibody-mediated - Type II
Which type of hypersensitivity?
Deposition of immune complexes (Ag/Ab) in tissues
Immune complex-mediated - Type III
Which type of hypersensitivity?
T cell-directed mechanisms of tissue injury
Cell-mediated - Type IV
Which Type I phase - acute or late?
5-30 mins
Subsides within 60 mins
Vasodilation
Vascular leakage
Smooth muscle spasm
Type I acute phase
Which Type I phase - acute or late?
2-24 hours
No additional exposure
Eosinophils, neutrophils, basophils, monocytes, CD4+ T cells
Mucosal epithelial cell damage
Type I late phase
Which hypersensitivity?
- Rapid immune reaction (mins)
- Preformed antibodies (IgE) to allergen
- IgE binds FceRI on mast cells
- Allergen crosslinks bound IgE molecules + triggers release of histamine
- Acute (< 1 hr) + late (2 hr - days) phases
- Local or systemic (anaphylaxis)
Immediate - Type I hypersensitivity
Name the key immune elements of Immediate - Type I hypersensitivity (6)
CD4+ T cells
B cells
IgE antibodies
Th2 cytokines
Mast cells + mediators (acute phase)
Eosinophils + neutrophils (late phase)
What are the Th2 cytokines involved in Immediate - Type I hypersensitivity?
IL-4
IL-13
IL-5
What is the primary mediator of mast cells?
Histamine
What leads to the following:
Increased vascular permeability
Smooth muscle contraction (airways)
Increased mucous gland secretion
Produced by mast cells, basophils, platelets
Histamine
What are the 3 factors that play a role in the clinical presentation of Immediate - Type I hypersensitivity?
- Amount of IgE present (bound to mast cells)
- Amount of allergen encountered
- Route of allergen contact/entry
Susceptibility to which reaction has a strong genetic component?
Immediate - Type I
Which types of reactions are most common with LAs?
Immediate - Type I
Cell-mediated - Type IV
Which LA is most likely to cause an allergic reaction?
Esters (since they are metabolized to PABA)
How fast do Immediate - Type I symptoms occur after giving an injection to someone who is allergic?
Minutes
Which type of hypersensitivity?
Responsible for many antibody-mediated autoimmune diseases
Antibody-mediated - Type II
Name the 4 types of antigens involved in Antibody-mediated - Type II hypersensitivity
Foreign antigens
Pathogen antigens
Alloantigens
Own antigens
Which antigen in Antibody-mediated - Type II hypersensitivity?
Bind to cells and act as haptens
Foreign antigens
Which antigen in Antibody-mediated - Type II hypersensitivity?
Cross-react with self antigens - molecular mimicry
Pathogen antigens
Which antigen in Antibody-mediated - Type II hypersensitivity?
Blood group antigens in transfusion reactions, erythroblastosis fetalis
Alloantigens
Which antigen in Antibody-mediated - Type II hypersensitivity?
Auto-antigens in autoimmune diseases
Own antigens
What are the 3 types of mechanisms for Antibody-mediated - Type II hypersensitivity?
- Complement-Dependent
- Antibody Dependent Cell-Mediated Cytotoxicity (ADCC)
- Antibody Mediated Cellular Dysfunction
Which mechanism for Antibody-mediated - Type II hypersensitivity?
Opsonization for digestion/phagocytosis by macrophages
Ex: hemolytic anemias, transfusion rx
Complement-Dependent
Which mechanism for Antibody-mediated - Type II hypersensitivity?
Targets are lysed by leukocytes with Fcgamma receptors (neutrophils)
Ex: Graft rejection
Antibody Dependent Cell-Mediated Cytotoxicity (ADCC)
Which mechanism for Antibody-mediated - Type II hypersensitivity?
Antibodies directed against cell-surface receptors
Ex: Graves Disease (agonistic Abs), Myasthenia Gravis (antagonistic Abs)
Antibody Mediated Cellular Dysfunction
Which hypersensitivity?
- IgM + IgG bind soluble antigen, activate complement, and are normally cleared by phagocytic cells in liver + spleen
- Complexes not easily cleared deposit in tissues
- Localized (arthus rxn) + systemic (serum sickness, SLE)
- Diverse antigens (exogenous, endogenous)
Immune complex-mediated - Type III hypersensitivity
Name the antigens involved in Immune complex-mediated - Type III hypersensitivity (5)
Foreign antigens
Pathogen antigens
Autoantigens
Tumor antigens
Environmental antigens
Which antigen in Immune complex-mediated - Type III hypersensitivity?
Example is SLE
Autoantigens
Which antigen in Immune complex-mediated - Type III hypersensitivity?
Examples are post-streptococcal glomerulonephritis, Hep B virus
Pathogen antigens
Which antigen in Immune complex-mediated - Type III hypersensitivity?
Examples are antisera, antibodies
Foreign antigens
Which antigen in Immune complex-mediated - Type III hypersensitivity?
Example is Aspergillus in farmer’s lung
Environmental antigens
Name the 4 factors that affect immune complex deposition in Immune complex-mediated - Type III hypersensitivity
- Amount of antigen
- Physicochemical properties of antigen + antibody
- Ratio of antigen/antibodies
- Ability of phagocytes to remove circulating immune complexes
What cells is Cell-mediated - Type IV hypersensitivity mediated by?
Antigen specific T cells
Name the cells involved in Cell-mediated - Type IV hypersensitivity
CD4+
CD8+
Which cells act through cytokines and activation of other cells (like macrophages) in Cell-mediated - Type IV hypersensitivity?
CD4+ T cells
What is Cell-mediated - Type IV hypersensitivity also called?
Delayed-type hypersensitivity
Which cells act through cytotoxicity in Cell-mediated - Type IV hypersensitivity?
CD8+ T cells
Name an example that triggers delayed-type Cell-mediated - Type IV hypersensitivity
Tuberculin reaction
Name 2 examples that trigger contact-type Cell-mediated - Type IV hypersensitivity
Poison ivy
Nickel (and other small metal ions)
What are some things people can have hypersensitivities/allergies to in dentistry?
- Antibiotics, anesthetics, analgesics (Type I rxn)
- Certain metals (Type IV contact rxn)
- Latex products (Type I + IV rxns)
An assay to detect hypersensitivity to metals (MELISA) measures the reactivity of what?
T cells