MOD 5&6 - General Principles of Immune Response Flashcards Preview

MOD > MOD 5&6 - General Principles of Immune Response > Flashcards

Flashcards in MOD 5&6 - General Principles of Immune Response Deck (54):

what are pattern recognition receptors

used to identify simple pathogen and initial engagement with the infection and inform the adaptive system


what does pattern recognition receptors include

inclusive term for antigen recognition receptor in innate system


examples of pattern recognition receptors

pathogen-associated molecular patterns (PAMPs), danger associated molecular patterns (DAMPs)


what are the 2 groups of pattern recognition receptors

1) cell surface and intracellular receptors
2) fluid-phase soluble molecules


what is fluid-phase recognition molecules

c-type lectin family


what is lectin

Lectins offer a way for molecules to stick together without getting the immune system involved, which can influence cell-cell interaction.


what does fluid-phase recognition molecules do?

recognition of microbial complex carbohydrates and bind to them via carbohydrate-recognition domains (CRDs)

role in neutralisation of pathogen, role in recruitment of adaptive response


an example for fluid-phase recognition molecules



which cytokines are the 1st cytokine produced in an infection which makes you fell unwell and muscle ache

IL 1


what is the function of macrophages

phagocytose and kill bacteria

produce antimicrobial peptides & inflammatory cytokines


what is the function of plasmacytoid dendritic cells

produce large mount of interferon - anti-tumour and anit-viral


what is the function of myeloid dendritic cells

produce IL-12 and IL-10


what is the function of natural killer cells

kill foreign and host cells which have low MHC+ self peptides


what is MHC

major histocompatibility complex (antigen presented to recongise foreign pathogen)


what is the function of natural killer T cells

lymphocytes with both T cells and NK surface marker - recognise lipid antigens of intracellular bacteria


what is the function of neutrophils

phagocytose and kill bacteria and produce antimicrobial peptide


what is the function of mast cells and basophils

release inflammatory markers in response to PAMPs


what is the function of epithelial cells as immunological deference

produce anti-mircobial peptides - produce mediator for local innate immunity


what is the core features for adaptive immune system

- unique antigen receptors found on each lymphocyte


what is primary lymphoid organs

lymphocyte development and selection

where the initial immune respond will take place - B cell will return to bone marrow and become long living & T cell will circulate the body in search for pathogen


what is secondary lymphoid organs

immune response


how does the adaptive system create diversity of antigen receptors for the B and T cells

T and B cells receptors are coded by genes that are fragmented so they can change shapes by combination of different receptors


how is antigen of pathogens are being presented?

antigens are being internalised (engulfed etc) - broken down to peptides - peptides associate with newly snythesised class 2 MHC molecules - transport back to the surface of the cell - if foreign peptide, then recognised by T helper cells and are activated - T helper cells produce cytokines needed by B cell etc - innate and adaptive system activated


what are histocompatibility antigens

glycoproteins found on the surface of cells which an individual unique


what prevent organ transplant

the unique histocompatibility antigens


how many types of MHC are there

2 - class 1 & class 2


what are function o MHC

T cells only see antigen in association with MHC - MHC responsible for presenting antigenic peptides to T cells


which type of cell does MHC class 1 protein present to

cytotoxic T cells


which type of cell does MHC class 1 protein present to

helper T cells


what are the function of B lymphocytes

secrete antibodies - humoral immunity


what are the different types of T cells

killer/cytotoxic T cells (to kill) - cellular immunity

helper T cell - secrete cytokines to control immune response - help B and T cells

suppressor T cells - damp down immune respone


how can cytotoxic T cell achieve the killing purpose?

bind to infected cell with antigens presented on the cell surface

perforin secreted by cytotoxic T cells makes holes in infected cell's membrane

infected cell lose cell integrity and so cell death


which 2 interleukins are responsible for allergic reaction?

IL4, IL5


which interleukin is responsible for autoimmune response



definition of hypersensitivity

Undesirable, damaging, discomfort-producing and sometimes fatal reactions produced by the normal immune system (directed against innocuous antigens) in a pre-sensitized (immune) host.


what are the 4 different types of hypersensitivity

Type 1 - IgE mediated reaction

Type 2 - cytotoxic reaction

Type 3 - immune complex reaction

Type 4 - Cell mediated reaction (DTH)


how is Type 1 hypersensitivity generated

IgE mediated mast cell and basophil degranulation - release inflammatory mediators


what is clinical features of type 1 hypersensitivity

fast onset (15-30 mins), weal and flare, can have late response after 1st


what is the severe type 1 hypersensitivity



how does type 1 hypersensitivity work?

allergen posessed by B cells which produce IgE

IgE cross link with Fc receptors on sensitised mast cell

mast cells then release inflammatory mediators eg histamine & synthesis lipid mediators


what are the effect of type 1 hypersensitivity

histamine - bronchial tree constriction, fluid leakage, hypotension, purulent secretion and diarrhoea


what is early phase response of type 1 hypersensitivity

mast cells has FC receptor presented at high density, cross-linking of Fc receptors by allergen leads to activation of mast cell - degranulation (inflammatory mediators, synthesis of lipid mediators)


what are some examples of inflammatory mediators which will be released from degranulation?

histamine, kallikerin (bradykinin)


what are late phase response of type 1 hypersensitivity

- basophils (same function as mast cells but over long time scale)

- eosinophils (release cytotoxic protein - major source of tissue damage in allergic response )

- T cell responses (both early and late response) (cytokine production, another major source of pathogenesis in allergic responses)


what is type 2 hypersensitivity

antibody-mediated cytotoxic reactions (binding of antibody to target antigen on cell membrane - activation of complement cascade resulting in cell lysis & resulting in phagocytosis % destruction


what can activate type 2 hypersensitivity

initiated by IgM or complement-binding IgG


what cells are usually affected?

haematopoietic cells


what cause type2 hypersensitivity

blood group incompatibility, autoimmune haemolytic anaemias


which hypersensitivities can penicillin cause?

All 4 types


what is type 3 hypersensitivity?

immune complex reactions


how is type 3 hypersensitivity caused?

1 IgG + Ag = AgAb complex
2. FcR in complex bind C1q
3. Complement activation leads to generation of activated complement fragments
4a. C5a - attractant for neutrophils
4b. C3b - Opsonin
5. Attempted phagocytosis of complexes - release of enzymes, oxygen radicals
6. Consequence is tissue damage


some examples for immune complex reactions

B12 deficiency - binding to intrinsic factor


what is type 4 hypersensitivity

T cell mediated - CD4+ cells (MHC class II)


how does type 4 hypersensitivity work?

initially perivascular infiltration of lymphocytes & monocytes

langerhan's cell present antigen to T cells which release cytokines - recrtiment of macrophages

activated macrophages cause tissue damages

requires previous exposure to antigen