Immunology Flashcards
Summary of general B cell development
Haemopoietic stem cell -> VDJ rearrangement -> negative selection -> mature cells move to BM periphery -> activation leads to plasma or memory cell formation
Function of B cell Abs
- Neutralization (bind bacteria and prevent their entry into cells, neutralize toxins)
- Opsonise extracellular bacteria (FCC receptors on phagocytes or NK cells can bind FCC portion and kill)
- Complement activation (Ab/Ag complex)
Molecules expressed by mature B cell
BCR (IgM and IgD)
MHCll
CD40
CD19
Describe Ab response to protein
Ag specific B cell binds Ag Ag internalized (endocytosis) High density specific Ag presented Primed T cell interact with B cells Clonal expansion of plasma cwlls
Three pathways to making plasma cells / Ab
T independent. - limited range of Ag -> neutralizing
Extra follicular - w/wout T cell depending on Ag, low affinity Ab is formed
Germinal centers - high affinity Ab, plasma cells and memory cells
How long does it take to make T cells
Roughly 1 week
Describe T cell development
In thymus VDJ rearrangement - diversity MHC restriction - positive selection Lineage commitment Eliminate autoreactive cells - negative selection
Define cytokines
Small soluble proteins secreted by one cell that can alter behavior/properties of the cell itself or other cells
CD4 subsets and their primary cytokines
Th1 - IFN-y (TNFa)
Th2 - IL-4
Th17 - IL-17
Treg - TGF-B
What types of pathogens do Th1 cells target
Intracellular eg. Viruses and bacteria
What are the effector functions of Th1 cells
Activate macs (NO,O2-,proteases) Kills chronically infected cells (bacteria released) Induce T cell proliferation Induce macrophage differentiation Activate endothelium (diapedesis) Chemotaxis for macs
What pathogens do Th2 cells respond to
Extracellular pathogens
Function of Th2 cells
Activate B cell
Promote isotope switching ESP to IgE
Role of Treg cells
Suppress activation and development of naive T cells
What do CD8 cells release to kill cells
Perforin Granzymes Granulysin FAS ligand (INF-y and TNF)
Action of perforin
Aids in delivering granule contents to cytoplasm of target cell
Action of Granzymes
Serine proteases that activate apoptosis
Action of granulysin
Antimicrobial action to induce apoptosis
What does MAC do
Creates a pore in bacterial cells membrane leading to osmotic lysis of bacteria
Role of phagocytes in killing bacteria
Phagocytose
Kill bacteria in phagolysosome
Immunological processes that protect neonate from infection at birth
IgG - maternal, across placenta
IgA and IgG - breast milk ingestion, neutralize organisms, IgG crosses gut epithelium
Effector cells responsible in type l diabetes
Autoreactive CD4, CD8
T cell mediated type IV hypersensitivity
Self Ags recognized by immune cells in IDDM
Pancreatic islet cell Ag
Pancreatic B-cell proinsulin/insulin
Glutamic acid decarboxylase
Active immunity is ..
Production of Abs as a result of exposure to antigen (natural or artificial Ag)
Passive immunity is …
The direct transfer of Abs formed by another person/animal
Effect of maternal Ab on vaccination of neonate
Limit replication of live virus
Mask B cell epitopes = prevent vaccine binding to infant B cells
Allows generation of memory B cells
Does not inhibit T cell responses
T dependent Ags must contain..
Protein component
Effector cells responsible for tissue damage in type 1 diabetes
- Autoreactive cd4 cells and cd8 cells
- type 4 hypersensitivity
Self- antigens recognized that leads to type 1 diabetes
- pancreatic beta cell hormone pro insulin
- pancreatic islet cell antigen
HLA group in diabetes type 1
Dr3/4
3 main functions of antibodies
- neutralization
- opsonisation
- activation of compliment
What does the Mac do?
Forms a pore in the bacterial membrane
Leads to osmotic lysis of the bacteria
