Revision Flashcards
What are the 2 types of Immunity
Adaptive
Innate
2 types of adaptive immunity
T cell (mediated)
B cell (humoral)
2 types of innate immunity
Bloodborne
Physical barriers
Which blood cells are involved in innate immunity
Neutrophils
Macrophages
Basophils
Eosinophils
Natural Killer Cells
What is the purpose of the complement system
enhances the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism
It promotes inflammation and attacks the pathogen’s cell membrane
What part of the immune system is the complement system in
Part of the innate immune system but can be bought into action by antibodies generated by the adaptive immune system
Where are complement proteins synthesized e.g. C3, C5
liver- they circulate in the blood as inactive precursors
What is the end result of the complement cascade (3)
- Stimulation of phagocytes to clear foreign and damaged material
- Inflammation which attracts additional phagocytes (self-amplification)
- Activation of cell-killing membrane attack complex
Role of neutrophils
Engulf and destroy
Role of Monocytes/macrophages
Engulf and destroy
Role of eosinophils
fight parasitic infections
Role of basophils
Release histamine
Role of Lymphocytes
Attack Specific pathogens
Role of plasma cell
produce antibodies
Describe humoral adaptive response to a pathogen
- After being exposed to a pathogen, in the humoral adaptive immune response, antigen presenting cells pick up the pathogens antigens.
- They internally process this antigen and present it on a MHC-2 receptor on their cell membrane which is able to bind to a T helper 2 cell.
- This cell then processes this antigen and releases cytokines such as IL-4 and IL-5, (which activate B cells that have receptors specific for the same antigen. The activated B cell undergoes clonal expansion, dividing to produce a large population of identical B cells.) to cause a naïve B cell to differentiate and undergo class switching to obtain B cell receptors that are specific to the antigen from the pathogen.
- This specific antigen related B cell is then going to further differentiate to either plasma cells (release specific antibodies) or recruited as B memory cells incase the pathogen is exposed again
Describe cell mediated immune response
Does not involve antibodies, involves activation of cytotoxic T lymphocytes and the release of cytokines in response to those particular antigens
Used to destroy damages or virally infected body cells
Cytotoxic T cells bind to an MHC class 1 receptor on an apoptotic cell as it is expressing this pathogenic antigen
The connection with the CD8+ cell and the apoptotic cell releases cytokines that bring about the destruction of the cell
Could also have T helper 1 cells which recognise antigens on pathogens and stimulate cytotoxic T lymphocytes to kill pathogen
What is a dendritic cells
Antigen presenting cell
Their main function is to process antigen material and present it on the cell surface to the T cells of the immune system.
What are CD8+ cells
CD8+ cells are primarily responsible for recognizing and destroying infected or abnormal cells, such as virus-infected cells or cancer cells. They do this by recognizing and binding to specific proteins, called antigens, that are present on the surface of these cells. Once a CD8+ cell has bound to an antigen, it can release toxic substances, such as perforin and granzymes, that cause the targeted cell to undergo apoptosis, or programmed cell death.
CD8+ cells are activated when they encounter antigen-presenting cells, such as dendritic cells or macrophages, which have captured and processed antigens from invading pathogens or abnormal cells. Once activated, CD8+ cells undergo clonal expansion, which allows them to produce large numbers of identical T cells that are specific for the same antigen. These can then destroy more infected cells due to releasing toxic substances. Some of these activated CD8+ cells also differentiate into long-lived memory T cells, which can quickly respond to future encounters with the same antigen.
Role of IgG
Common Ig found in serum and colostrum
Role of IgA
Common Ig found at mucosal surfaces
Role of IgM
Common B cell receptor Ig
Role of IgE
Common Ig for allergic response
Role of IgD
Unknown specific role, thought to be B cell function
Roles of antibodies
- neutralization of microbes and toxins
- Opsonisation and phagocytosis of microbs
- Antibody-dependent cellular cytotoxicity
- Complement activation -> lysis of microbes, phagocytosis of microbes opsonised with complement fractions, inflammation
