Introduction Flashcards
introduction
Which cells link the innate and adaptive immune systems by presenting antigens to T cells?
Dendritic cells
What are the professional antigen presenting cells?
macrophages, dendritic cells and b cells (all present antigen to T cells to initiate immune response)
What is immunity?
Defense of the host against foreign pathogens (antigens)
What are the 3 categories of host defense?
Physical & chemical barriers
Cells of innate immune system
Cells of adaptive immune system
What are the chemical barriers against infection?
- Tears
- Sweat
- Mucus
- Stomach acid
- Antibodies
- Antimicrobial peptides
What are physical barriers against infection?
Skin
Mucosal surfaces- upper and lower respiratory tract, intestinal epithelium, vaginal epithelium
What cells are considered granulocytes?
neutrophils, basophils, eosinophils and mast cells (although mast cells are not involved in granulocytosis)
What are the key cells of the innate immune system?
macrophages- monocytes
dendritic cells
granulocytes
natural killer cells
What are the tissue-specific macrophages?
- Alveolar and Peritoneal macrophages
- Kuppfer cells
- Osteoclast
- Microglial in brain
- Histiocytes
What are monocytes?
a monocyte is a circulating precursor of
macrophages in blood
they leave bloodstream and become more specialised and mature into macrophages
Describe macrophages
Phagocytosis and killing of microorganisms
Activation of T cells and initiation of the immune
response (they are a professional antigen presenting cell meaning they present antigen to T cell to activate them and induce immune response (adaptive))
What are the functions of neutrophils?
phagocytosis
degranulation- granules can be expelled to kill other cells when invaded
involved in neutrophil extracellular traps (NETs)
Discuss neutrophils structure etc.
they are polymorphonuclear
they are a granulocyte
Short life span (hours)
Very important at “clearing” bacterial infections
What links the innate and adaptive immune systems?
the immune system acts in synergy to fight infections
T cells and apc interactions link innate and adaptive immune response
There is close synergy between the two systems with the adaptive response greatly improving the efficiency of
the innate response and the innate response setting the scene for activation of the adaptive response
Discuss granulocytes other than neutrophils
eosinophils and mast cells - found in tissues
basophil - found in circulation
all play a role in allergic inflammation and destruction of parasites via degranulation
eosinophils- produce antihistamines and have a double-lobed nucleus
Discuss dendritic cells
found in lymphoid tissue
they are professional antigen presenting cells
specialised dendritic cells called Langerhan cells are in the epidermis of skin
initiate adaptive immunity through activation of T cells
dendritic cells are the most potent stimulators of T cells (most common)
What cells have characteristics/functions of innate and adaptive immunity so can’t be classed as one or the other?
Gamma-delta T cells
Innate lymphoid cells
Natural killer T cells
What are the cells of the adaptive immune response?
Lymphocytes- b cells and t cells
B cells produce antibodies and are also professional antigen presenting cells
There are helper T cells and cytotoxic T cells (natural killer T cells?)
there are memory B and T cells - produced by immune response, they reside and are long-term and are reactivated when infected by same pathogen
there are regulatory b and t cells
Discuss T-lymphocytes
Helper T cells are involved in macrophage enhancement and b cell activation
Cytotoxic T cells release toxic granules to kill infected cells - affect tumour cells and cause apoptosis
Discuss B-lymphocytes
there are memory cells which are long-lived and have an enhanced response to future infection
there are plasma cells which are short-lived and provide immediate protection by secreting large amounts of antibodies that immobilise the pathogen (they stick to pathogen to make it visible to cytotoxic T cell which kills them)
Discuss immunoglobulin and epitope
immunoglobulin is usually attached to b cell receptor
epitope is attached to antigen
epitope specificity is important for specific immune response
What is the difference between lymphocytes and leukocytes?
Both of white blood cells but only lymphocytes are b and t cells
Discuss immune system
If immune system cannot go back to homeostasis(normal) then this can cause chronic inflammation, hypersensitivity, immunodeficiencies and immunosuppression
Immunosuppression is a drop in the response of the immune system to infection. Immunodeficiency is a lack in the immune response of the body to an infection
