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33 Cards in this Set

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What is the immune response?
Recognition of a pathogen and a response to eliminate it.
two types of responses: innate and adaptive
Adaptive immune response
specific:each cell only recognises specific antigen(s)
Memory: recognise those previously encountered
Self from non self recognition
What is an antigen?
any molecuele which can be specificly recognised by B ot T cells
most are proteins
pathogenic orgnsisms may have several antigens
immune response
occurs when an antigen is recognised by a lymphocyte that is capable of responding
lymphocytes are concentrated at lymph, blood, fluids from lungs/GI
What makes up the adaptive immune response?
lymphocytes
B cells: Humoral immunity: produce antibodies
T cells: cell mediated, direct contact w antigen or via cytokines
3 types of antigen receptor molecules
Immunoglobulins
T cell antigen receptors
Major Histocompatability complexes -enable self recognition
name three effects on pathogens as a result of immune system
Neutralization-binding to antibody
Phagocytosis-englufed
Cytotoxicity-killing
3 characteristics of t cell antigen receptor
Located on surface of T cell
Specific to particular antigen
TCR never secreted
Self recognition
Regulated by presence of Major Histocompatability complex
or
human leucocyte antigen
what is MHC restriction?
When T cells recognise cell bound antigen in association with MHC molecules
MHC class and t cell response
the class of MHC will determine which T cell will respond.
Antigen presenting cells express class 2 so present to T helpers
Infected body cells express class 1 and present to T cytotoxic cells
To ensure self recognition works?
Adaptive immune response usually require both B and T cell recognition. B cells can interact directly with antigen but need signal from T helpers
Hypersensitivities
Type 1: IgE mediated (allergy)
Type 2:Tissue specific
Type 3: Immune complex
Type 4: Cell- mediated
Type 1 Immediate (Allergy)
Mediated by IgE and mast cells
Mast cells: found in most tissues, particualy connective, serve as stroage for histamine and other inflam mediators
how does the allergic response occur?
IgE molecules bind to the surface of mast cells, resulting in them releasing histamine etc
(by products of complement activation also cause this)
Type 2 hypersensitivity -tissue specific
Damage or destruction of target cell through action of antibody against antigen on cell surface
IgG or IgM antibodies involved
Differences between type 2 and type 3
Both mediated by IgG and IgM antibodies. but in type 3, antibodies are directed against widely distributed or suluble antigens. type 2 is cell surface antigens
3 types of type 2 reactions to RBC abd platelets.
Incompatible blood transfusion-recipient sensitive to anitgens on surface of donor cells
Haemolytic disease of newborn
Autoimmune haemolytic anaemias-sensitive to self erythrocytes
Give and example of a drug induced hypersensitivity
Quinine, coats cells.
the drug plus cell surface proteins is antigenic.
Antibodies and complement cause death and lysis
Name three other drug induced hypersensitivities
Platelets: thromboctyopenic purpura
Granulocytes:granulocytopenia
Erythrocytes: haemolytic anaemia
Name three type 2 reactions against tissue antigens
Goodpastures syndrome: glomerular and lung basement membrane
Insulin dept diabetes: insulin cells, or insulin recepts
Myasthenia gravis: Ach receptors
Type 3 Hypersensitivity
most type 3 hypersensitivity rxns caused by formation of antibody/antigen (immmune) complexes.these form in blood, but then may be deposited on bv lining.
Describe the mechanism of type 3 hypersensitivity reactions
the immune complexes trigger inflamm process.
-complement system
-cytokines
-basophils and platelets
Factors effecting sit of complex deposition
Vascular permeability
Blood pressure/ turbulence
Antigen affinity for specific tissue
Size of comlex
Class of Ig in complex
What is Autoimmunity
Type 2 or 3 hypersensitivity mechs involved.
Breakdown of self tolerance
Genetic predisposition
Three ways this could occur?
Autoimmunity produces disease lesion
Tissue damage as reslut of disease leading to autoantibody prodn
Something causes both the lesions and autoantibodies
Give 4 examples of pathogenic antibodies
Thyroid autoimmune disease:antibodies mimic TSH
Diabetes:Antibodies to insulin receptors(rare)
Male infertility:Antisperm antibodies
Exampls of pathogenic antibodies cont
Pernicoius amaemia: autoantibody prevents uptake of Vit B12 from gut
Self tolerance failure
Molecular mimicry by cross-reactive microbial antigens stim autoreactive B and T cellls
Foreign antigen directly stim B cell without T cell help
Cytokine disregulation
Inapprop MHC class expression
What is Primary(congenital)
immunodeficiency
Infants who are born without one or more components of the immune system
-developmental defects in the production of the cless or proteins in immune system.
What is secondary(aquired)
immunodeficiency?
as a result of diseases such as diabetes, influenza, measals, cancer.
from viruses(HIV)
following transplant/result of chemotherapy
HIV immune damage
death of infected T4 cells
Category A: asymptomatic
Category B: symptomatic
Stages of HIV infection-indicator conditions
Candida infn of airways
CMV eye infection
Tuberuculosis
Pneumonia