9 Leukocytes Flashcards
why does the proportion of leukocytes differ in cell types
Number depends on the health of the individual at the time
what do cells become
lymphoid or myeloid
Mononuclear or PMN/granulocytes
Lymphoid Mononuclear cells
- Nk cells
- CD8+T cells
- CD4+ T cells
- gamma delta cells
- B cells
Myeloid Mononuclear cells
- dendritic cells
- monocytes: macrophages or dendritic cells
Myeloid PMN/granulocytes cells
- neutrophils
- eosinophils
- basophils
- mast cells
where do all cells come from
Cells all come from hematopoietic stem cells
what can cells become
depending what their exposed to, whether they go down the lymphoid progenitor route or myeloid progenitor route
Macrophage
phagocytosis and activation of bacterial mechanisms. Antigen presentation
Dendritic cell
antigen uptake in peripheral sites (great due to long dendrites). Antigen presentation in lymph nodes
Neutrophil
phagocytosis and activation of bactericidal mechanisms
Eosinophil
(adaptive immune system needs to be on to recognise the pathogen) killing of anti-body coasted parasites – extracellular digestion
Mast cell
release of granules containing histamine and other agents
what do macrophage contain
Granules stuffed full of enzymes – activated when a pathogen is engulfed
Complement of other molecules - macrophage
proteases, cytokines
what neutrophils contain
Granules with enzymes to cut, also have specific granules
complement of other molecules - neutrophils
leukotrienes, cytokines, prostaglandins
macrophage killing
Bacteria binding to endocytic receptors of macrophages induce their engulfment a and degradation
Bacterial components binding to signalling receptors of macrophages
neutrophil killing
Neutrophil expresses receptors for many bacterial constituents
Neutrophils engulf and digest bacteria to which they bind
Recognition through antibodies – needs to be later on in process as require antibodies from adaptive
what do eosinophils contain
Contain granules stuffed with enzymes – released to damage a large pathogen
complement of other molecules - eosinophils
cytokines, enzymes, prostaglandins, leukotrienes
what does eosinophils do
Extracellular digestion
what do mast cells contain
preformed mediators
what is an example of a preformed mediator
histamine
what happens when mast cells are activated
generates newly synthesised molecules
complement of other molecules - mast cells
cytokines, prostaglandins, leukotrienes
what do mast cells lead to
inflammation
which cells are long lived
mast cells
eosinophils
which cells are short lived
neutrophils - but they are constantly remade
which cells are sessile
stationary - mast cells sit in tissues
which cells are mobile
eosinophils
neutrophils
when do natural killer cells not kill
- Interaction with uninfected healthy cell
- Interaction with healthy allogenic cell of very similar HLA-C type
when do natural killing cells kill
- no interaction of MHC class 1 expression
- Interaction with healthy autologous cell
- Interaction of healthy allogenic cell of different HLA-C type
Cytotoxicity - Cytotoxic T cells
Collision and nonspecific adhesion
Specific recognition redistributes cytoskeleton and cytoplasmic components of T cell
Release of lytic granules at cell contact site
when does the cytotoxic T cell recognise
Cytotoxic T cell recognises complex of viral peptide with MHC class 1 and kills infected cells
what are the cytotoxic effector molecules
- perforin
- granzymes
- granulysin
- Fas ligand
Regulation - helper T cell (CD4)
Naïve CD4 T cell forms proliferating T cell then to immature effector T cell
what do immature effector T cell form
TH1 cell
TH2 cell
what do the TH1 cells do
macrophage activation, B cell activation and production of opsonising antibodies e.g. IgG1
what do the TH2 cells do
general activation of B cells to make antibodies
how do T cells function
by making contact with other cells and inducing them
which T helper cell is formed when
Depending on naïve T cell signal depends what T helper it will become
what does TH17 make
interleukin 17
what does Treg make
regulate immune response
effect of IL-17
inflammatory response
what activates a T cell
Co-stimulatory signal and specific signal
when does T cell becomes anergic
Specific signal alone
when is there no effect the T cell
Co-stimulatory signal alone
how are naive T cells activated to give effector T cells - MHC class 1
naive CD8 T cell recognises peptide + MHC class 1 proliferation and differentiation of CD8 T cells
how are naive T cells activated to give effector T cells - MHC class 2
naive CD4 T cell recognises peptide + MHC class 2 proliferation and differentiation of CD4 T cells
effector functions of T cells - virus infected cell death
cytotoxic T cells travel to infected tissue where virus-infected cells present specific antigen
virus-infected cell dies by apoptosis
effector functions of T cells - bacteria killed
effector TH1 cells travel to infected tissue where macrophages infected with or containing bacteria present specific antigen
activated macrophage kills bacteria
effector functions of T cells - antitoxin antibodies
effector TH2 cells interact with antigen-specific B cells in lymphoid tissue
plasma cells make antitoxin antibodies
effects of antibody production on bacterial toxins
neutralisation - ingestion by macrophage
effects of antibody production on bacteria in extracellular space
opsonization - ingestion by macrophages
effects of antibody production of bacteria in plasma
complement activation - lysis and ingestion
Antibody-dependent cell mediated cytotoxicty (ADCC)
Antibody binds antigen on surface of target cells
Fc receptors on NK cells recognise bound antibody
Cross linking of Fc receptors signals the NK cell to kill target cell
Target cell dies by apoptosis
