Immunology Flashcards
Innate immunity
Instinctive
Non-specific response
Not dependent on lymphycoytes
Present from birth
Adaptive immunity
Specific
Acquired/learned
Memory
Requires lymphocytes and ab
Blood sample consists of
Centrifuge forms 2 layers:
Upper - plasma, straw-coloured
Middle - Leukocytes, White fluffy
Leukocytes
Lymphocytes
Phagocytes
Auxillary cells
Origin of leukocyte cells
Multipotent hematopoietic stem cell (haemocytoblast)
Leukocyte cell differentiation goes through
Bone marrow to thymus to blood
Cells of immune system
Polymorphonuclear leukocytes (Neutrophil (neutral stain-liking), eosinophil (acidic-stain liking), basophil (basic-stain liking)) Mononuclear leukocytes (Monocyte (kidney shaped nuclei), T-cells, B-cells)
When monocytes matures through tissues into blood it becomes
Macrophage
T cell types
T-regs
T-helper
Cytotoxic
Th17
B-cells become activated into
Plasma cells
Other leukocytes
Mast cells Natural killer cells |(specialised T cells) Dendritic cell Kupffer cell - liver Langerhans - skin
Soluble factors
Complement
Antibodies
Cytokines and chemokines
Complement
Group of 20 serum proteins secreted by liver that need to be activated to be functional
Modes of action - Direct lysis, attract leukocytes to site
Antibodies
Immunuglobulins
IgG
Y-shaped
Constant and variable regions
Most predominant Ig in human serum - 70-75%
IgM
Pentamer-shaped
10% of Ig in serum
Mainly found in blood, too big to cross endothelium
Mainly primary response
IgA
15% of Ig in serum
Monomer
Mucous secretions such as saliva
Secretory component sticks them together
IgE
0.05% of Ig in serum
Basophils and mast cells
Allergic reactions
Cytokines
[roteins secreted by immune and non-immune cells
Interferon - viral infections (alpha, beta and gamma)
alpha and beta - virus infected cells
gamma - activated th1 cells
Interleukins - IL1 (Pro-inflam), IL10 (Anti-inflam)
Colony stimulating factors - stimulate bone marrow to produce leukocyte precursors
TNF alpha and beta - Mediate inflam and cytotoxic reactions
Chemokines
Chemotactic cytokines Tell leukocytes where to go in body Group of 40 proteins CXCL - Attract neutrophils CCL - Attract monocytes, lymphocytes, eosniphils, basophils CX3CL - attract T and NK cells XCL - attract T cells
Innate immunity
1st line of defence non-specific barrier to antigen instinctive present from birth slow response no memory
adaptive immunity
specific to antigen
learnt behaviour
memory to specific antigen
quicker response
Innate immunity cells
Neutrophils and macrophages
complement
Innate immunity physical barriers
skin
bronchi - mucus, cilia
gut - acid
Inflammatory response
breach of barrier (tissue damage or infection during trauma)
Response - coagulation (stop bleeding), acute inflam (leukocyte recruitment), kill pathogens, neutralise toxins, limit pathogen spread, clear pathogens/dead cells, proliferation of cells to repair damage, remove blood clot (remodel extracellular matrix, re-establish normal structure and function of tissue
Inflamamtion
Series of reactions that brings cells and molecules of the immune sytem to sites of infection or damage
Hallmarks - Increased blood supply, increased vascular permeability, increased leukocyte extravasation
Acute inflammation
complete elimination of a pathogen followed by resolution of damage, diappearance of leukocytes and full regen of tissue
Chronic inflam
persistent, un-resolved inflam
Sensing microbes
In blood - monocytes, neutrophils
In tissues - Macrophages, dendritic cells
PRR - Pattern recognition receptors (on cells)
PAMP - Pathogen-assocated molecular patterns (on microbe)
PRR bind to PAMP
TLR - Toll-like receptors
Lectin receptors
Scavenger receptor
Complement activation pathways
Classical - Ab bound to microbe
Alternative - C binds to microbe
Lectin - activated by mannose-binding lectin bound to microbe
Complement functions
Lysis of bacteria directly by MAC
Bond to bacterial membrane and coat it (opsonization)
Chemotaxis
Phagocytosis leukocytes
Macrophages, neutrophils, dendritic cells
Mechanisms of microbial killing
Oxygen-dependent - ROI (Reactive oxygen intermediates) - superoxides converted to hydrogen peroxide then OH free radical which kills bacterial DNA
Nitrix oxide - vasodilation (viagra) increase extravasation but also anti-microbial.
Oxygen independent - Lysozymes, proteins (defensins insert temslves into membranes), TNF.
Adaptive immunity
Antigen specificity and diversity
Immunological memory
Specific non-self recognition
Adaptive immunity
Cell mediated T cells - intracelular microbes
Humoral B cells (Ab) - extracellular microbes
Adaptive immunity
Thymus - primary lymphid tissue (T cells)
Bone marrow - primary lymphoid tissue (B cells and APCs)
Spleen, lymph nodes, MALT - Secondary lymphoid tissue
Cell-mediated immunity
Interlay between APCs and T cells
Requires cell-to-cell contact
Also requires MHC (Major histocompatibility complex) and Instrinsic/extrinsic antigens
Recognise self or non self
T lymphocytes
Only respond to presented antigens
T cells that recognise self-antigens are killed in the foetal thymus (T cell selection)
TCR (T cell receptor) recognises foreign antigens in association with MHC
MHC
Display peptides from self or non-self proteins
MHC
Coded for by HLA genes (Human leukocyte antigen)
MHC 1 and 2
MHC 1 - Glycoproteins on all nucleated cells, Displays intrinsic antigens, CD8 Tc cells
MHC 2 - Glycoproteins only on APCs, Displays extrinsic antigens, CD4 Th cells
MHC 3 - Code for secreted proteins (complement)
Link between innate and adaptive immunity
MHC
T cell activation
T cell then: divides (clonal expansion), differentiates (matured/active), effector functions, memory cells
Can become CD4 (Th) or CD8 (Tc)
Tc activation
CD8 + MHC1 = Tc
Th1 activation
CD4 + MHC2 = Th1
Humoral adaptive immunity B cell activation
B cells express membrane-bound Ig (monomeric - IgM or IgD)
B cells that recognise self are killed in
Bone marrow
B cells present Ag to T cells via MHC
MHC 2
B cell division is known as
Clonal expansion
B cell differentiates into
Plasma cells (AFC - Antibody forming cell) Memory B cells (Bm)
Lymphoid tissue of the body
Neck
Armpit
Groin
Antibody functions
Neutralise toxin by binding to it
Increase opsonisation - phagocytosis
Activate complement
Vaccination
Tetanus vaccination (tetnaus toxoid from clostridium tatni causes muscle spasms/contractions)