Immunology Flashcards
Parent, undifferentiated cells
Self-renew, “immortal” - can outlive 6x, daughter cells have function
Totipotent
All cells have stem cell properties
Erythrocytes
No nucleus or ER and live for 120 days, only have a sac of gas
Neutrophils
Migrate towards infection (chemotaxis) half life is hours
Lymphocytes
Are cytotoxic T cell - target cell instructed to die by T cell as T cell has specific antigen recognition which generates immune response (target molecule)
Macrophages
Ingest my phagocytosis
Humoral immunity
Anything soluble - immunoglobulin or antibody
Cytokines
Low Mr and are secreted - proteins that stimulate or inhabit cell differentiation and proliferation - communicate with haematopoetic cells
Interleukins
A group of cytokines that enable communication between leukocytes
Chemokines
Structurally related substance that induce chemotaxis in neutrophils and activation of leukocytes, much smaller
Interferons
Soluble glycoproteins of cytokines, interfere with viral inections
Antibodies
Multi-chain glycoproteins that are produced by beta-lymphocytes and contain a very variable antigen binding site and a functional/constant region
Complement
Soluble proteins that “complement” the action of antibodies, can also kill pathogens directly and are mainly produced by the liver
Innate immune response
No learning or memory. Can identify foreign things, no capacity to earn, pattern recognition receptor, react to generalities - evolutionary immunity to infection NK cells macrophages Neutrophils Complement cells Dendritic cells
Pattern recognition receptors
Toll-like receptors
Receptors conserved in evolution
TLR and PRR play a key role in signalling DANGER to immune system
PRRs also play a role in several physiological states
Adaptive or required immune response
All learned and memory - takes a while to produced enough cells to fight infection Learning Memory Specific antigen receptors T and B cells
Lymphocytes
T cells, B cells, NK cells
Cause specificity of immune system, large nuclei but whole barely bigger than RBC. Found in blood, tissue and lymph
Very stable - 20% of circulating leukocytes
Differentiate from common precursor - must undergo maturation to be functional
T cell
Precursor in bone marrow but must migrate to thymus to mature, express specific antigen receptor (TCR), different functional subclasses. Important in activating B cell responses, phagocyte killing of intracellular bacteria by innate system, kill virally infected cells
Helper T cells
CD4
Function to produce cytokines that support the immune response
Cytotoxic killer T cells
CD8
Function to kill virally infected cells - instruct target cell to die by clubbing membrane and chromatin collapses
What if you have no T cells?
DiGeorge syndrome - thymus does not develop, so not mature T cells produced. Immunoglobulin levels disturbed, causing candidiasis, pneumonia etc. Can survive to adulthood on innate system but virus fighting is poor, no antibodies.
B cells
Only cells producing antibodies (immunoglobulin), produced and mature in bone marrow (self/non-self testing) and express immunoglobulin (antibody) as surface antigen receptor complex. B cells and product are central to attacking extracellular pathogens e.g. bacteria. Found in peripheral blood and part of adaptive humeral response. Activate complements and opsonising (coating) bacteria in antibodies so that it can be recognised and undergo phagocytosis. Intermediate stage between introduction dn infection.
No B cells
X-linked infantile hypogammaglobulinaemia and show recurrent bacterial infection,but can be treated. IGMO initially taken from mother. B cells must learn to make own IGMO - no B cells from mother in bloodstream, so declines over time
Transient hypogammaglobulinameia - full IMGO at 6 months, but mother’s has a half life of 3 months
Can be treated with pofaltic antibiotics, blood transfusion or gene therapy to address fundamental genetic defect
Natural killer cells
Large granular lymphocytes - Innate lymphoid cells (ILCs). Detect virus infected cells by changes in cell surface molecules, kill using apoptosis and rare in blood. Express MHC molecules, exploits humeral immune system, have receptors identifying IMGO. Undergo editing - your own MHC is good, not bad -> self. Therefore, ability to infect virally infected cells and kill them is unique to you, looks like learning, but just ensures they are the right receptors for you.