Cells and Organs of the Adaptive Immune System Flashcards
list and describe 2 characteristics of the adaptive/acquired immune response
- specificity: tailored response to increase effectiveness
- memory: increased speed of and more robust response
list and give 2 examples each of the 2 types of specialized cells of the adaptive immune system
- lymphocytes: B and T cells
- antigen presenting cells: monocytes (become macrophages) and dendritic cells
where are the cells of the adaptive immune response born and matured?
primary lymphoid organs: either the bone marrow (of bursa of fabricius) or the thymus
where do the cells of the adaptive immune system work?
secondary lymphoid organs
what are 3 secondary lymphoid organs? (just give 3 examples here)
- lymphatics and lymph nodes
- spleen
- MALTs: mucosa-associated lymphatic tissues
what are primary lymphoid organs? describe
specialized organs where lymphocytes are formed and mature; and where B and T cells acquire their specific antigen receptor (like school)
what are secondary lymphoid organs? describe
organs and tissues where mature lymphocytes are maintained; and where adaptive immune responses are initiated (like work)
where do all immune cells originate from?
bone marrow!
what is the bone marrow?
the medulla of long bones and some irregular bones like the pelvis and ribs
what is in yellow bone marrow?
mostly fat; not relevant to immune system
what happens in red bone marrow?
hematopoiesis (generation of red and white blood cells)
what gives rise to all blood cells?
hematopoietic stem cells in red bone marrow
what causes the distribution of red bone marrow to vary?
species and age
what is the big daddy of all hematopoietic cells?
the pluripotent hematopoietic stem cell; could literally become ANY blood cell
what 2 cells can pluripotent hematopoietic stem cells differentiate into (that give rise to all others)
either common lymphoid progenitor cells or common myeloid progenitor cells
what do all T cells, B cells, and NK cells arise from?
common lymphoid progenitor cells
describe B cells that exit the bone marrow
naive (not exposed to antigen of interest) but mature (would know what to do when encounter antigen for first time)
once mature, naive B cells exit the bone marrow, where do they go? what do they do there?
travel the secondary lymphoid organs to participate in immune responses by differentiating into antibody-producing plasma cells
what happens to B cells as they mature?
they acquire their B cell receptor
describe the B cell receptor
located on the surface of the B cell; is a co-receptor complex so in order to stimulate a response, an antigen must bind to both the BCR and have costimulating components
what do B cell receptors (BCRs) do for B cells?
confer specificity to recognize and response to non-self antigen
how do B cells recognize antigen? contrast to T cells
B cells recognize antigen in NATIVE form!! just as they enter the body; but T cells recognize linear peptides presented by APCs and other cells
describe B cell activation
naive B cells bind antigen and multiply in a process called clonal expansion, where the daughter cells have the same BCR as the parent, resulting in many plasma cells able to recognize the same antigen
what are mature, activated B cells called?
plasma cells; also called professional cells that secrete antibodies
where are plasma cells located?
various lymphoid organs
describe T cell maturation
born in bone marrow, but must exit bone marrow and travel to thymus to differentiate into thymocytes; then exit the thymus as mature, naive T cells
once they exit the thymus, where do mature, naive T cells go? what do they do?
travel to secondary lymphoid organs to participate in immune responses and differentiate into effector cells
compare the thymus in younger animals to older animals
thymus much larger in younger animals than older animals
describe the more detailed process of birth and maturation of T cells in the thymus (3)
- lymphoid progenitors from the bone marrow seed cortex, or thymocytes, interact with epithelial cells in the cortex of the thymus
- these thymocytes mature as they move toward the medulla of the thymus, where they interact with medullary epithelial cells, macrophages, and dendritic cells
- then exit the thymus as mature, naive T cells
what do T cells gain as they mature?
their T cell receptor (TCR)
describe the TCR
located on the surface of the T cell, confers specificity to help immune system distinguish between self and non-self and recognize and respond to non-self antigen
describe T lymphocyte activation
T cells bind antigen, multiply a lot in a process called clonal expansion, where daughter cells have the same TCR as parent, resulting in many cells able to recognize the antigen
where are activated T lymphocytes found?
various lymphoid organs
what are the 2 responses/processes of the adaptive immune system? what cell is involved in each?
- cell-mediated: T cells
- humoral: B cells
describe cell-mediated adaptive immunity (3)
- T lymphocytes target intracellular pathogens like viruses
- cytotoxic (CD8) T cells directly kill infected cells
- helper (CD4) T cells produce cytokines, activate humoral immunity and innate immune cells (conductors of adaptive response)
describe humoral adaptive immunity
B lymphocytes (plasma cells once activated) produce antibodies that can help destroy pathogens like extracellular bacteria, toxins, and viruses
