Immunology Flashcards
what is the structure of an immunoglobulin made of?
Y shaped antibody in which the 3 hypervariable branches ( stem + 2 arms) bind to different copies of the same antigen
- Framework of Y composed of the variable heavy chains & the stem: crystallizable fragments composed of constant heavy chains
- Arms: hypervariable antigen binding sites made of lights chains & disulfide bonds
what is a heavy chain and why is it important to the immunoglobulin structure?
it gives an antibody its family name -the framework region of heavy chains is both constant and hypervariable -types of heavy chain types include: G A M E D
what are light chains and why are they important to the structure of an immunoglobulin?
antigen binding sites that finds matching antigens and attaches to it
-very specific in structure: they can only bind to the same one antigen of one bacteria/virus
»_space; Both arms - bind to same antigen of that virus
what are the two types of systems that make up the immune system?
- innate immune system
2. adaptive immune system
What is the innate immune system?
exists from birth and is NOT “learned”
-genetically programmed to protect us from molecular components found in microorganisms
What are the four hallmarks of inflammation?
- Rubor (redness/erythema)
- Calor (heat/warmth)
- Dolor (pain)
- Tumor (swelling)
- patients will present with 2-3 out of the 4 signs
What is the adaptive immune system?
“learned” by T and B lymphocytes as a result of exposure to antigens
what are the two types of immunity?
- humoral immunity
2. cell-mediated immunity
what is humoral immunity?
- implying the involvement of antibodies
- the protective portion of the immune system found in the plasma of the blood (humor= cell-free body fluid orserum)
how does cell mediated immunity differ from humoral immunity?
cell mediated immunity response does NOT involve antibodies
-involves the activation ofphagocytes,T-lymphocytes, and often the release of various cytokinesin response to an antigen
what is cell-mediated immunity directed primarily at?
- microbes that survive inphagocytesand
2. microbesthat infect non-phagocytic host cells
which type of immunity is most effective in removing virus-infected cells?
cell-mediated immunity
aside from viruses, what else does cell-mediated immunity defend against?
• fungi • protozoans • intracellular bacteria • cancers *also involved in transplant rejection
what are the cellular components of the innate system?
phagocytes which are a group of immune cells specialized in finding/eating bacteria, viruses, dead cells
-4 types of phagocytes
what are the 4 types of phagocytes?
1. granulocytes > neutrophils > eosinophils > basophils (aka mast cells) 2. Macrophages > AKA tissue monocyte 3. dendritic cells > AKA phagocytic cells (the housekeepers) 4. natural killer cells
what are granulocytes and what is their function in the innate immune system?
neutrophils, eosinophils, basophils (aka mast cells)
-Attack rapidly & in large numbers (like a pawn in chess!)
what are macrophages and what is their function in the innate immune system?
macrophages start out as WBC (monocytes) -> once they enter blood = macrophages
- key player in alerting the rest of the immune system to invaders
- Slow to respond in attack but have a longer lifespan, are larger and have greater capacities
what are dendritic cells and what is their function in the innate immune system?
phagocytic cells that are the housekeepers which help activate the immune system
-also capable of filtering body fluids to clear them of foreign organisms & particles
what are the Humoral Components of the Innate System?
- consist of things cells release into the plasma *
- Physical barriers: skin (keratin), mucous membranes (mucus)
- Cytokines (released from white cells & attract inflam cells)
- Enzymes (lysozyme)
- Inflam. mediators released by macrophages, mast cells, and NK cells
- Interferon
- complement proteins
what is interferon and how is it important to the innate immune system?
chemical released by virus-infected/dying cells (inhibit viral replication)
-as an infected cell dies, it releases a chemical message that alerts other cells to keep viruses from replicating in other cells
what are complement proteins and how are they important in the innate system?
roughly 20 serum protein fragments made from the liver
- interact w/ antigens
- similar to clotting cascade
- activated by inflammatory process -> augment/amplify effects of the immune system
what effects are complement proteins responsible for?
- Bacterial opsonization
- Directs cell lysis
- Chemotaxis (trigger inflam)
- Attract and aid phagocytes
what is bacterial opsonization and how does it facilitate phagocytes?
opsonin- any molecule like immunoglobulin & complement proteins that targets an antigen for immune response
- the opsonins bind to an antigen on the invader (antigenic invader = bacteria/virus)
- flags invader bacteria/viruses by coating them w/ complement protein
- allows phagocytes to better recognize and engulf them
what are the cellular components of the adaptive immune system and how do they contribute to the adaptive immune response?
- B lymphocytes
- T lymphocytes
Lymphocytes interact w/ one another to process/retrieve data to carry out immune responses to antigenic stimuli
what are T lymphocytes and what is their role in the adaptive immune system?
control the adaptive immune response & produce antigen-specific cell mediated immunity with these functions:
- Scan intracellular environment for foreign invaders
- Directly kill virally or bacterially infected cells; also eradicate CA cells
- Activate other immune cells
- Remember a foreign invader they encountered decades ago (memory)
what are the negative effects of T cells in immune responses?
- transplant rejection
- some allergic rxn
ex) gluten intolerance - all autoimmune diseases
ex) DM, MS, RA
Helper T cells (TH cells)
express CD4 surface glycoprotein on their membranes which initiate activity of:
- B cells
- macrophages
- NK cells
- cytotoxic T cells
- other T helpers
- must be activated by effector helper cell
Regulator T cells (Tr cells)
suppressor cells that modulate immune system by:
-maintaining tolerance to self antigens, thus restraining autoimmune disease
how do regulator T cells prevent autoimmune disease?
suppression or down regulate induction & proliferation of NK cells)
what are antigen-presenting cells in the adaptive immune system and what is their role?
- monocyte/macrophage
- dendritic cells
activates naive helper T cell in peripheral lymphoid tissue to make them into effector helper T cells
TH1 effector cell
defends against intracellular pathogens by secreting interferon-gamma and tumor necrosis factor-alpha
- activate macrophages to kill microbes located w/in macrophages’ phagosomes
- activate cytotoxic T cells
- ALSO stimulate B cells to secrete specific subclasses of IgG
TH2 cell
defends against extracellular pathogens
-secretes interleukins, stimulate B cells to make most classes of antibodies (IgE and subclasses of IgG) -> release local mediators
what is the effect of local mediators released by B cells stimulated by TH2 cells?
expel extracellular microbes & parasites from epithelial surfaces
ex) sneezing, coughing, diarrhea
Cytotoxic T cells (TC cells)
express CD8 surface glycoprotein
-induce apoptosis (lysis) of cells displaying epitopes of foreign antigen on their surface
what is an epitope?
*major key to antigen presentation:
antigen fragment from an invader which phagocytes such as dendrites display on surface to present to helper T cells
-subsequently activates helper T cells into armed effector T cells
what are types of cells that can be used as epitopes by cytotoxic cells?
-virus-infected cells
-cells containing intracellular bacteria/parasites
-cells exhibiting aberrant differentiation and antigens (dysplasia, neoplasia)
allogeneic cells in the process of graft rejection