Unit 4 - Immune System PART H & I Flashcards
Adaptive Immunity is the…
Second line of defense after innate response
Highly specific
Provides long lasting resistance to pathogens.
Two processes:
Describe how Adaptive Immunity is highly specific
- recognizes specific PATHOGEN and intiates a unique response to it.
- Depends on ability of T-cells, B-cells and antibodies to bind to (i.e. recognize) specific EPITOPES on ANTIGENS.
Describe how Adaptive Immunity provides long lasting resistance to pathogens.
antibodies and memory cells “remember” (i.e. have receptors for) the EPITOPES/ANTIGENS of pathogens they have encountered, and so are easily recruited upon subsequent infections.
Describe the Adaptive Immunity’s two processes:
- Cell-mediated immunity
2. Humoral (antibody mediated) immunity
Pathogen =
infectious agents that cause disease
Antigen =
any molecule that the body does NOT recognize as self (e.g. protein components of pathogen cell membrane/cell wall)
Epitope =
part of antigen that interacts with receptors on T lymphocytes, B-lymphocytes, and antibodies.
Adaptive Immunity - Cells
- T-lymphocytes
2. B-lymphocytes (B-cells)
Adaptive Immunity
- T-lymphocytes
a. Helper T cells (TH, also known as CD4+ cells)
i. Type 1 Helper T cells (TH-1 cells)
i. Type 2 Helper T cells (TH-2 cells)
b. Cytotoxic T cells (TC, also known as CD8+ cells)
c. Regulatory T cells (Treg)
Adaptive Immunity
- T-lymphocytes
a. Helper T cells (TH, also known as CD4+ cells)
direct/mediate adaptive immunity
- during embryonic dev., this 1 set of immature lymphocyte precursor cells (T cells), migrates from the bone marrow to the thymus gland, where they mature
Adaptive Immunity
- T-lymphocytes
a. Helper T cells (TH, also known as CD4+ cells)
i. Type 1 Helper T cells (TH-1 cells)
secrete INF-g (interferon-gamma) and IL-2 that activate macrophages and cytotoxic T-cells respectively.
mediate cell-mediated immunity
Activated T lymphocytes…
attack & destroy virus-infected cells & help regulate other immune cells
Adaptive Immunity
- T-lymphocytes
a. Helper T cells (TH, also known as CD4+ cells)
i. Type 2 Helper T cells (TH-2 cells)
secrete IL-4, IL-5, IL-6 that help activate B cell growth, differentiation and antibody production.
mediate Humoral (antibody-mediated) immunity
Cytotoxic T cells (TC, also known as CD8+ cells)
- role: defend the body against intracellular pathogens
- responsible for CELL-MEDIATED IMMUNITY when they attack & destroy cells that destroy cells that display MHC-I antigen complexes
- prevents the reproduction of intracellular invaders such as viruses, some parasites, & some bacteria
Adaptive Immunity
- T-lymphocytes
b. Cytotoxic T cells (TC, also known as CD8+ cells)
Once activated, attack and destroy virus infected cells that have the specific antigen
Cause apoptosis of infected host/target cells by: release of cytotoxic (pore-forming) molecules (PERFORINS and GRANZYMES); and by activating FAS a death receptor protein on the host cell)
Granzymes
activate an enzyme cascade that induces the cell to commit suicide (apoptosis)
Adaptive Immunity
- T-lymphocytes
c. Regulatory T cells (Treg)
prevent excessive immune responses by suppressing other lymphocytes
- (DON’T directly attack pathogens & infected cells & they also bind to MHC-I complexes (like helper T cells)
Adaptive Immunity
- B-lymphocytes (B-cells)
responsible for creating humoral immunity
Naïve cells are exposed to antigen creating a primary
immune response, and then upon future exposures to the
same antigen, secondary responses occur
after activation by TH-2 cells and clonal expansion, will
develop into:
a. Plasma cells (effector cells)
b. Memory B Cells
Adaptive Immunity
- B-lymphocytes (B-cells)
After activation by TH-2 cells and clonal expansion, will
develop into:
a. Plasma cells (effector cells)
- cells that produce antibodies (from their B-cell receptors,
BCRs).
b. Memory B Cells
- long lived cells that enter circulation
- allow for a more rapid response to a secondary infection (memory B cells have B-cell receptors that can bind to antigen, stimulating the production of antibodies more directly)
Adaptive Immunity
- B-lymphocytes (B-cells)
a. Plasma cells (effector cells)
cells that produce antibodies (from their B-cell receptors,
BCRs).
Adaptive Immunity
- B-lymphocytes (B-cells)
b. Memory B Cells
long lived cells that enter circulation
allow for a more rapid response to a secondary infection
(memory B cells have B-cell receptors that can bind to
antigen, stimulating the production of antibodies more
directly)
Antibody
describes what the molecules do: work against foreign bodies (antigens)
- also called IMMUNOGLOBINS –> describe what the molecules are: globular proteins that participate in the adaptive immune response
