Lecture 1- intro Flashcards
Who is the father of vaccination and what disease did he work with?
Edward Jenner & smallpox
Name 2 things the immune system is good for
1- Fighting infections (bacteria, viruses, parasites, fungi)
2- surveying for tumors and rejecting tumors
What happens if the immune system goes rogue?
autoimmunity
allergies
transplant rejection
Where is the immune system located?
circulates through the body all the time, lymphatic system- lymph nodes are where immune responses may be initiated
- spleen
- bone marrow and thymus (primary lymphoid organs)
Who are the major players of the immune system?
cells- hematopoietic stem cell– myeloid, lymphoid, erythroid lineages
name the cells in lymphoid lineage
B cells
T cells
NK cells
name the cells in myeloid lineage
granulocytes: neutrophils, eosinophils, basophils
phagocytes/monocytes: dendritic cells, macrophages, mast cells
name the cells in erythroid lineage
megakaryocyte
erythrocyte
name 2 other components of the immune system
cytokines
complement
describe cytokines
- “hormones” of the immune system
- secreted by cells upon exposure to a pathogen; secreted by one cells and act on another cell (autocrine or paracrine)
- interleukins- communication between leukocytes- can cause or inhibit activation
- cause fever, swelling, recruitment of cells, amplification of immune response
name the cell types of innate immunity
all phagocytes, granulocytes, NK cells
name the cell types of adaptive immunity
B cells
T cells
describe innate immunity
- molecules and cells that distinguish host from infectious agents by recognizing conserved motifs
- rapid, activated within minutes to hours of exposure
- not significantly increased by previous exposure (constant, no memory)
- does not rearrange DNA to form highly specific receptor
describe adaptive immunity
- cells with very specific receptors for an unlimited number of targets
- effective only after a delay of several days
- has immunological memory- enhanced responsiveness upon re-encounter of same pathogen
- rearrange DNA to form highly specific receptors
Which is worse- lacking innate immunity only or lacking adaptive immunity only?
lacking innate immunity is worse- can kill host
describe the receptors of B and T cells
B cells have highly specific antigen-binding site
T cell receptor: antigen-binding site is highly variable
T cell receptor is always at cell surface
what is an antigen?
a molecule (often a protein derived from a pathogen) recognized by the immune system as foreign, you generate an immune response to it
what is an antibody?
protein produced by B cells, circulate in blood and lymph, binds very specifically to a given pathogen when they come upon it
- aka immunoglobulin
what is epitope?
more specific part of antigen, the part that is actually bound by the antibody
name the primary lymphoid organs and their function
- thymus- T cells
- bone marrow- B cells
primary organs are where selection occurs (B and T cells, auto-reactive)
name the secondary lymphoid organs and their function
lymph nodes
where activation of the cells occur, clonal expansion when activated
primary lymphoid organs function in _____
secondary lymphoid organs function in ____
selection
activation
what is clonal expansion?
the selection and expansion of a receptor specificity that makes a cell clonally expand (signal sent to nucleus of B cell for clonal expansion, every offspring of that B cell will have the same receptor)
- in the end, there is so much expansion that there has to be contraction
describe the early events of the innate immune system when infection starts
- surface wound introduces bacteria, which activate resident effector cells to secrete cytokines
- vasodilation and increased vascular permeability allow fluid, protein, and inflammatory cells to leave blood and enter tissue
- infected tissue becomes inflamed- redness, swelling, pain
- large reserves of neutrophils are stored in bone marrow and are released when needed to fight infection
- neutrophils travel to and enter infected tissue- they engulf and kill bacteria, the neutrophils die in tissue & are engulfed and degraded by macrophages
describe the transition from innate to adaptive immune response
transition begins with the migration of dendritic cells to the draining lymph nodes
dendritic cells are carrying pathogens, T and B cells specific for these antigens will undergo clonal expansion in the lymphoid tissue
(lymph nodes are architectually organized into B and T cell centers)
describe process of clonal expansion and selection
1- lymphocyte clones mature in generative lymphoid organs, in the absence of antigens
2- clones of mature lymphocytes specific for diverse antigens enter lymphoid tissues
3- antigen-specific clones are activated (“selected”) by antigens
4. antigen-specific immune responses occur
describe the phases of the adaptive immune response
- antigen recognition
- lymphocyte activation (clonal expansion and differentiation)
- antigen elimination (antibodies and effector T cells)
- contraction, homeostasis (apoptosis)
- memory
