Immunopathology Flashcards
What can the immune system be divided into?
Innate and adaptive
What cells does the innate immune system involve?
- Neutrophils
- Complement and PRRs (pattern recognition receptor)
- Dendritic cells
What cells are involved in the adaptive immune system?
- B cells (memory)
- T cells High affinity antibody
What are the 2 important roles of the innate immune system?
- Recognise threat
- Engulf and destroy threat
Which cells of the innate immune system recognise threat?
Professional Antigen presenting cells (APCs):
- Dendritic cells
- Macrophages / monocytes
How do Antigen Presenting Cells work?
When a pathogen is detected, these APCs will phagocytose the pathogen to form many different fragments of the antigen –> these fragments are then presented
How do cells of the innate immune system engluf and destroy threat?
Via phagocytosis
Phagocytes:
- Macrophages
- Neutrophils
Granulocytes:
- Neutrophils
- Eosinophils
- Mast cells
- Basophils
How do granulocytes and phagocytes differ?
Granulocytes are phagocytes, that is they are able to ingest foreign cells such as bacteria, viruses and other parasites. Granulocytes are so called because these cells have granules of enzymes which help to digest the invading microbes.
What are the proteins of the innate immune system?
- Cytokines
- Acute phase proteins
- Complement
What are cytokines?
Chemical signals which modulate cell activity or attract cells (chemokines)
What are acute phase proteins?
Defined as proteins that change their serum concentration by >25% in response to inflammatory cytokines –> Opsonise or present pathogens to the immune system
What are complement proteins?
A cascade of proteins with multiple functions; opsonisation, killing, activation, chemoattraction
What are PRRs?
Pattern Recognition Receptors:
- Each immune cell carries identical receptor of a given type
- These receptors recognise conserved molecular structures known as pathogen- or damage-associated molecular patterns (PAMPs and DAMPs)
What are 2 examples of PRRs?
- Toll-like receptor (TLR)
- Inflammasomes (NLRP3)
What are PAMPs?
Derived from pathogens –> Fragments of pathogen such as bacterial cell wall
E.g. LPS
What are DAMPs?
Derived from host cells –> including tumor cells, dead or dying cells, or products released from cells in response to signals such as hypoxia
What are inflammasomes?
The inflammasomes are innate immune system receptors and sensors that induce inflammation in response to infectious microbes and molecules derived from host proteins (PAMPs and DAMPs)
What is a central feature to the adaptive immune response?
- UNIQUE antigen receptor found on each lymphocyte
- In response to infection this lymphocyte undergoes CLONAL expansion
- High degree of specificity
What is the function of B lymphocytes?
Develop the potential to secrete antibodies: humoral immunity
What is humoral immunity?
The aspect of immunity that is mediated by macromolecules found in extracellular fluids such as secreted antibodies, complement proteins, and certain antimicrobial peptides
What are the different types of T lymphocytes?
- Killer/cytotoxic
- Helper
- Suppressor
Function of killer/cytotoxic T lymphocytes?
Able to kill –> cellular immunity
Function of helper T lymphocytes?
- Secrete growth factors (cytokines) which control the immune response
- Help B lymphocytes and T lymphocytes
Function of suppressor T lymphocytes?
May dampen down immune response
Overview of physiological immune response
What is immunodeficiency?
Inappropriately decreased response to danger signals –> increased susceptibility to infection
What is autoimmuniy and autoinflammation?
Inappropriately increased response to danger signals –> can cause damage