principles immunology Flashcards
What is the immune system
Network of specialised cells, tissues and soluble factors that co-operate to kill and eliminate disease-causing pathogens and cancer cells
variolation definition
Exposure of an individual to the contents of dried smallpox pustules from infected patient
two major classes in the immune system
cells (leukocytes, white blood cells) and soluble factors (humoral factors)
the main classes of soluble factors
Antibodies
Complement System Proteins
Cytokines
Acute Phase Proteins
the main classes of cells
phagocytes, lymphocytes, mast cells, eosinophils and basophils
what is an antibody
protein produced in response to an antigen
overview of the complement system
family of approx 30 proteins, produced in liver and circulate blood as inactive, the enter infected/inflamed tissues and become active. Complement proteins can enzymatically cleave and activate other downstream Complement proteins in a biological cascade.
overview of cytokines
collection of small proteins and peptides, produced in response to infection, inflammation and tissue damage, they modulate the behaviour of cells and play a key role in coordinating the immune system
functions of monocytes, macrophages and neutrophils
phagocytosis - they ingest and kill bacteria and fungi, ingest and clear debris from the body, and are also important sources of cytokines
what do monocytes do
circulate in blood and then migrate to peripheral tissues and differentiate into macrophages
what do macrophages do
they are long lived tissue resident cells that have the additional functions of:
Limit inflammation
Involved in tissue repair and wound healing
Involved in Antigen Presentation
what do neutrophils do
circulate in blood and are rapidly recruited into inflamed, damaged and infected tissues
what do dendritic cells do
in peripheral tissues in immature state mature and migrate into secondary lymphoid tissue where the play a key role in antigen presentation
mast cells, basophils and eosinophils
highly granular cells, release histamine, heparin and cytokines which results in acute inflammation, they are they defence system against large pathogens
what do mast cells do
reside in tissues and protect mucosal tissues
what do basophils and eosinophils do
circulate in blood, recruited to sites of infection by inflammatory signals
what do natural killer cells do
large granular lymphocytes, kill tumour cells and virally infected cells can also kill antibody -bound cells and pathogens
overview of T and B cells
circulate in blood, lymph and secondary lymph tissue, inactive and mature, active when in come into contact with pathogen/antigen
what do B cells do
Responsible for production and secretion of antibodies to defend against extracellular pathogens
what do T cells do and what are the two types of T cells
Key role in defense against intracellular pathogens (viruses, mycobacteria) Helper T cells Key regulators of the immune system Cytotoxic T cells Kill virally infected body cells
what is immunological memory and what cells regulate it
Once the adaptive immune system has recognised and responded to a specific antigen, it exhibits life-long immunity to this antigen
regulated by memory T cells and B cells
what is the innate immune system
rapid and general response to different pathogens
what is the adaptive immune system
Slow response (days)
Response is unique to each individual pathogen
Mediated by T and B lymphocytes
Responsible for generating Immunological Memory
what is primary lymphoid tissue the sight off
leukocyte development
what is secondary lymphoid tissue the sight off
Sites where adaptive immune responses are initiated
Contain T cells, B cells and Dendritic cells
overview of the lymphatic system
System of vessels draining fluid from body tissues (‘lymph’)
Lymph nodes are positioned regularly along lymph vessels – trap pathogens and antigens in lymph
what is lymphoedema, what are the causes and what does it increase the risk of
Also known as lymphatic obstruction, is a condition of localized fluid retention and tissue swelling caused by a compromised lymphatic system, which normally returns interstitial fluid to the thoracic duct and then the bloodstream.
causes are - inherited, cancer treatment and parasitic infections
increases risk of infection
what are the two major mechanisms of cell to cell communication in the immune system
- direct (receptor to ligand contact)
2. indirect (production and secretion of cytokines)