module 01 section 03 (adaptive immune system) Flashcards
what are the 6 unique features of the adaptive IS?
(1) discrimination
(2) diversity
(3) specificity
(4) specialization
(5) memory
(6) self-limitation
define “discrimination” w respect to the adaptive IS
the ability of the adaptive IS to discriminate btwn self and non-self prevents injury to the host during response to pathogens
define “diversity” w respect to the adaptive IS
the adaptive IS responds to a wide variety of microbes and molecules
define “specificity” w respect to the adaptive IS
the adaptive IS is capable of distinguishing subtle differences amongst foreign antigens
define “specialization” w respect to the adaptive IS
- the immune response generated is antigen-dependent, ensuring optimal defense against each type of microbe
- as mature cells need time to be activates there is a lag period in response time of 4-5 days
define “memory” w respect to the adaptive IS
the adaptive IS has enhanced responses to a microbe following repeated exposures (I.e. it has an immunological memory)
define “self-limitation” w respect to the adaptive IS
cells of the adaptive IS allow microbe-activated immune responses to return to their basal state (allowing for homeostasis)
list the cells of the adaptive IS
B and T lymphocytes
describe T cell activation
- to elicit an adaptive immune response, t-cells require activation by professional antigen-presenting cells (APCs)
- APCs have the ability to present processed antigens through major histocompatibility complex molecules (this will be covered later)
how are T-cells distinguished from other lymphocytes?
by the presence of the T-cell receptor on the cell surface
describe the funtion of T-cells in terms of immunity
list the types of T-cells
- T-cells are important for both cell mediated and humoral immunity
- all T-cells recognize the processed antigen in complex with the major histocompatibility complex molecules, via the T-cell receptor
- Naive T-cells can develop into helper T-cells or cytotoxic T-cells
list and define the two types of adaptive immunity
(1) cell mediated: any adaptive immune response in which antigen specific t-cells have the main role
- i.e. focused on the adaptive immune response to antigens expressed in/on cells
(2) humoral immunity: the antibody-specific mediated immunity made in a humoral immune response (mediated by substances found in the bodily fluids, e.g. secreted antibodies)
- i.e. focused on the adaptive immune response to antigens found circulating freely
what are the helper T-cell co-receptors?
what is the function of these cells?
- express CD4 co-receptors
- these are the regulatory cells (have a role in maintaining or supressing immune cells/reactions)
- are also involved in antibody production
what are the cytotoxic T-cell co-receptors?
what is the function of these cells?
- express CD8 co-receptors
- these are the effector cells (short-lived, activated cells that respond to a stimulus and effect change)
- i.e., are involved in killing of target cells, such as virally infected cells
where do T-cells originate?
like all immune cells, T-cells origionate from the hematopoietic stem cells in the bone marrow
explain (generally) the process of T-cell maturation
- progenitor T-cells propagate and undergo differentiation in the thymus medullary and cortex
- naive T-cells (which express neither CD4 or CD8) develop from double negative cells into double positive cells (briefly expressing both CD4 and CD8 receptors)
- then they differentiate into mature T-cells, expressing the T-cell receptor with either CD4 or CD8 (i.e. are now single positive receptors)
what does T-cell maturation rely on?
the development of the T-cell receptor
explain in detail the types of helper T-cells and their corresponding functions
(1) Th1: activate macrophages and are responsible for cell-mediated immunity
(2) Th2: induce mature B-cells to differentiate into plasma B-cells to produce antibodies (which are responsible for humoral immunity)
how are B-cells distinguished from other lymphocytes?
by the presence of the B-cell receptor on the cell surface
describe the function of B-cells in terms of immunity
- humoral (antibody-mediated) immunity consists of B-cells
- these are responsible for secreting or expressing antibodies on their surface
- B-cells also express other characteristic surface markers including B7 (regulatory molecule) and CD40 (molecule critical for antigen-stimulated B-cell survival)
where do B-cells origionate?
like all immune cells, B-cells origionate from the hematopoietic stem cells in the bone marrow
explain the process of B-cell maturation
occurs in many stages in the bone marrow, each defined by a unique gene expression pattern
list and define the main classes of B-cells
(1) immature B-cell: express cell-surface immunoglobulin (Ig) M
(2) mature B-cell: express both cell-surface IgM and IgD
list and define the main subclasses of mature B-cells
(1) plasma B-cells: secrete antibodies following antigen stimulation
- these circulate plasma and lymph as a part of humoral immunity
(2) memory B-cells: involved I secondary antibody response; a fundamental principle in vaccination
define “antibodies”
how many classes are there? list them.
- aka immunoglobulins (Ig)
- Y-shaped proteins used by the immune system to neutralize foreign antigens
- there are 5 classes: IgA, IgD, IgE, IgG, IgM
where is IgA found and what is its role?
- found in high concentrations in mucous membranes such as respiratory passages, GI tract, saliva, tears
- acts primarily as a neutralizing antibody to prevent the attachment of pathogens to muscosal epithelial cells
- responsible for the antimicrobial activity in secretions
where is IgD found and what is its role?
- exist in small amounts in the blood
- has no known biological effects
- expressed on the cell surface together with IgM on mature B-cells that have not been exposed to antigens
where is IgE found and what is its role?
- found in the lungs, skin and mucous membranes
- plays a role in anaphylaxis through the release of histamine from granulocytes (following exposure to allergens)
- protects against parasitic infection
where is IgG found and what is its role?
- found in all bodily fluids fighting bacterial and viral infections
- its the only antibody that can pass throught the placenta to provide immunity to the fetus
where is IgM found and what is its role?
- largest antibody
- found mainly in the blood and lymph fluid
- this is the first antibody to be made by the body to fight a microbial infection
- also an excellent complement activator
