Immune System Flashcards
Functions: MACROPHAGE
AGRANULOCYTE
Large phagocytic cell - engulfs foreign particles & pathogens.
Functions: EOSINOPHIL
Granulocyte
Kill antibody-coated parasites.
Involved in allergic response.
Functions: BASOPHIL
GRANULOCYTE
Releases chemicals involved in inflammation - HISTAMINE (causes VASODILATION)
Short-term inflammation (Allergy/irritation).
Functions: NEUTROPHIL
FIRST LINE DEFENCE
GRANULOCYTE
Phagocytic leukocyte.
(bacteria & fungi)
antigen presentation.
Functions: DENDRITIC CELL
processes antigen material & presents it on surface of other cells to induce an immune response.
Functions: MAST CELL
LEUKOCYTE (GRANULOCYTE) Mediates inflammation (HISTAMINE RELEASE) in response to large pathogens & allergens.
LYMPHOCYTES
AGRANULOCYTE
Large & mononuclear
B, T & NK cells.
GRANULOCYTES
ENZYMATIC granules
Release inflammatory mediators.
neutrophils (60%), eosinophils, basophils, mast cells
AGRANULOCYTES
MONONUCLEAR
INNATE & ADAPTIVE immune response.
LYSOSOMES.
MONOCYTES, LYMPHOCYTES, DENDRITIC cells.
PRIMARY LYMPHOID TISSUES & functions
Bone marrow & thymus
LYMPHOCYTE ORIGIN & maturation.
NO IMMUNE RESPONSE
SECONDARY LYMPHOID TISSUES & functions
TONSILS & ADENOIDS, Spleen, lymph nodes, appendix, Peyer’s patches
LYMPHOCYTE ACTIVATION -> IMMUNE RESPONSE.
LYMPH NODES
Lymph filters & site of adaptive immunity.
Circulating lymphocytes are activated when encounter pathogen.
Compare innate & adaptive immunity.
INNATE: 1/2nd line of defence FASTER response No memory Limited specificity Constant during response
ADAPTIVE: 3rd line defence SLOW response Memory Highly specific Variable Improve during response.
INNATE IMMUNITY:
NATURAL due to genetic factors or physiology.
NOT induced by infection or vaccination.
PREVENTS, DETECTS, DESTROYS.
Skin, mucous membranes, microbiota
PHAGOCYTOSIS, INFLAMMATION, DEGRANULATION.
granulocytes & monocytes
ADAPTIVE IMMUNITY:
Has MEMORY & occurs after exposure to an antigen either from a pathogen or a vaccination
SPECIFIC.
ANTIGEN PRESENTATION, CELL-MEDIATED, HUMORAL, ANTIBODIES, COMPLEMENT, MAC complex, MEMORY CELLS.
T & B cells (memory)
Antibodies
Which cell type is common to both the innate & adaptive response?
DENDRITIC CELLS
Immediate innate immune response
Physical/chemical barriers
Antimicrobial peptides
Complement system
Describe the classical pathway of complement system.
C1 binds Ag-Ab complex.
C2 & C4 split.
C4b opsonin.
Describe the alternative pathway of complement system.
C3b opsonin, C3a/C5a pro-inflammatory.
MAC complex.
Pathogen lysis.
State the conditions for complement inactivation
EGTA, complement inhibitors & heat 56 C.
What is the MAC complex
Membrane Attack Complex forms cytotoxic pores -> pathogen lysis.
INDUCED INNATE RESPONSE
Phagocytosis.
Cytokine production & inflammation.
TLR activation
NK cells
Describe phagocytosis
Regognition & attachment
Engulfment into a phagosome; fusion with lysosome forms PHAGOLYSOSOME ->
DEGRADATION.
Functions of CYTOKINES
Induce INFLAMMATION.
Regulate innate & adaptive immunity
Stimulate haematopoiesis
What structures produce cytokines.
MACROPHAGES, NEUTROPILS, T cells
Bone marrow stromal (stem) cells
Which cytokines are produced by macrophages
IL-1, IL-6, TNF
Describe phases of inflammation
HISTAMINE release by mast cells -> INFLAMMATION
VASODILATION & increased vascular permeability
Leukocyte migration
What is the purpose of inflammation?
Attract immune cells to infection site.
Bacterial LPS activate __ in ___ to induce ___
TLRs in macrophages, phagocytosis
Viral RNA activate __ in infected cells.
TLRs
INTERFERONS
ANTIVIRAL : act as pyrogens
Activate NK cells
TOLL LIKE RECEPTORS (TLRs)
PRRs which recognise conserved features of pathogen molecules.
Propagate antigen-induced signal transduction pathways.
NK cell activation by:
Cytokines (interferons) IFN-alpha & IFN-beta
Describe NK cell activity:
IFN activate IFN receptors on NK cells
Effector NK cells proliferate & differentiate
induce APOPTOSIS - kill virus-infected cells
Describe B cell development
- Generate BCR
- Negative selection
- BC migration & maturation
- BC activation & Ab prod.
Where are B cells produced & mature
Bone marrow
(A) Naive B cells encounter an antigen in a ____ ____ ____.
(B) Antigen-specific B cells are further activated by ____ __ cells.
(C) Some activated B cells proliferate in the ____ ____ & differentiate in ____ ____ which secrete ______. This is the ____ response.
(D) Other activated B cells migrate to and mature in a ____ ____ of the secondary lymphoid follicle. They differentiate into ___ ___ & secrete high-affinity isotype switching ___. Others differentiate into ____ ____ which posess high-affinity isotype-switched ___ ___. This develops the ____ response.
(A) Secondary lymphoid tissue
(B) Helper T cells
(C) primary follicle. plasma cells, IgM antibody primary response
(D) Germinal centre plasma cells antibodies memory cells antigen receptors secondary
Describe a TCR
2 polypeptide chains: αβ
Each w a variable & constant region.
V chain: 3 CDRs
Proteins of CD3 complex
What is a CDR
Hypervariable region
TCRs recognise:
short peptide fragments bound to MHC (Major Histocompatibility Complex molecules)
BCRs recognise:
Free antigens
MHC Class I
- where they are expressed
- function
ALL NUCLEATED CELLS
Binds TCR of CD8 T cells.
MHC Class II
- where they are expressed
- function
APCs (macrophages, B cells, dendritic cells)
Bind TCR of CD4 T helper cells.
T cell binds ___ ____
MHC complex
CYTOKINE
INTERCELLULAR COMMUNICATION
chemical messenger that regulates cell differentiation, proliferation, gene expression, and cell trafficking to effect immune responses
Perforin
destructive protein that creates a pore in the target cell; used by NK cells and killer T cells
NK cell
lymphocytes - cytotoxic: kill virus/tumour cells
ALLERGY
Immune reaction due to immediate hypersensitivities in which an antibody-mediated response occurs within mins of exposure to a harmless antigen.
LYMPH
Bathes tissues & organs with protective WBCs.
Does NOT contain erythrocytes
T(reg) cell
suppresses local inflammation & inhibits cytokine, antibody & stimulatory immune factor secretion.
IMMUNE TOLERANCE
HUMORAL IMMUNE RESPONSE
adaptive immune response that is controlled by activated B cells and antibodies
Antigen Presenting cells
immune cell that detects, engulfs, and informs adaptive immune response about an infection by presenting the processed antigen on the cell surface
pathogen-associated molecular pattern (PAMP)
Distinctive conserved features expressed by viruses, bacteria & parasites which differs from molecules on host cells.
mucosa-associated lymphoid tissue (MALT)
collection of lymphatic tissue that combines with epithelial tissue lining the mucosa throughout the body.
TONSILS, ADENOIDS, bronchus ALT, peyer’s patches, appendix, follicles in intestinal mucosae
Effector cell
A differentiated lymphocyte (B cells, plasma cell or cytotoxic T lymphocytes)
Hypersensitivities
spectrum of maladaptive immune responses toward harmless foreign particles or self antigens; occurs after tissue sensitization and includes immediate-type (allergy), delayed-type, and autoimmunity
T cell
lymphocyte that matures in the thymus gland
adaptive immune system
Cell-mediated immune response
Adaptive immune response carried out by T cells
Inflammation
localized redness, swelling, heat, & pain due to increased migration of leukocytes via blood to infection site due to VASODILATION
ANTIBODY
protein produced by plasma cells (immunoglobulins)
T(helper) cell
ADAPTIVE IMMUNE SYSTEM: binds APCs via MHC II molecules & stimulates B cells or secretes cytokines to initiate immune response.
T(cytotoxic) cell
ADAPTIVE IMMUNE CELL : directly kills infected cells via PERFORIN & GRANZYMES, & releases cytokines to enhance immune response.
INTERFERON
CYTOKINE - inhibits viral replication & modulates immune response.
Pattern Recognition Receptor (PRR)
molecule on macrophages and dendritic cells that binds molecular signatures of pathogens -> promotes PHAGOCYTOSIS.
Memory T/B cell
antigen-specific B or T lymphocyte that does not differentiate into effector cells during the primary immune response but can immediately differentiate into an effector cell upon reinfection (same pathogen)
CLONAL SELECTION
activation & dramatic proliferation of B cell variants corresponding to a specific BCR variant and the dramatic proliferation
B cell
lymphocyte that matures in the bone marrow and differentiates into antibody-secreting plasma cells
PASSIVE immunity
transfer of antibodies from one individual to another to provide temporary protection against pathogens
GRANZYME
PROTEASE - enters cells through PERFORIN & induces apoptosis in target cell.
Used by NK & killer T cells.
IMMUNODEFICIENCY
failure, insufficiency, or delay at any level of the immune system, which may be acquired or inherited
MONOCYTE
Leukocyte - circulates blood & lymph, differentiates into MACROPHAGES IN infected TISSUE.
OPSONISATION
enhances phagocytosis using proteins to indicate the presence of a pathogen to phagocytic cells
Autoantibody
Incorrectly marks self components as foreign stimulating an immune response
AUTOIMMUNE
inappropriate immune response to host cells or self-antigens
Immune tolerance
acquired ability to prevent an unnecessary or harmful immune response to a detected foreign body known not to cause disease or to self-antigens
PLASMA CELL
Secretes antibodies
Arise from B cells stimulated by antigens
Major histocompatibility class (MHC) I / II molecule
Protein on surface of all nucleated cells (I) or specific on APCs (II) that signals immune cells if a cell is infected.
Provides template into which antigens can be loaded for recognition by lymphocytes,
COMPLEMENT SYSTEM
~20 soluble proteins of innate immune system - ENHANCES PHAGOCYTOSIS, bores HOLES in pathogens & recruits lymphocytes.
Enhances adaptive response when antibodies are produced.
