50, adaptive, antigen processing

exam 2

what are the 4 steps of adaptive

antigen capture, processing, and presentation

helper t cell activation

b cell (humoral) or cytotoxic t cell (cell mediated) responses that eliminate invaders

generation of large populations of memory cells

what are released by cytotoxic t cells to attack an infected tumor cell and cause apoptosis

perforins or granzymes

what is antigen capture, processing, and presentation

the induction of the adaptive immune response requires the activation of antigen presenting cells

what are professional antigen presenting cells

dendritic

what are semi professional antigen presenting cells

macrophages

b lymphocytes

what are dendritic cells

full time antigen presenting cells

100x more effective at it than macrophages or B cells

what are dendritic cells the only ones capable of doing

activating naive CD4+ T cells

makiong them essential for initiating primary adaptive immune responses

Where are dendritic cells located

where the pathogens enter

Skin, mucosal surfaces, Respiratory, urogenital tract

what tissues are dendritic cells not found

present in all organs except the brain, eye, and testes

what are immature dendritic cells

constantly sample the enviornment

capture antigens via phagocytosis/endocytosis

where do dendritic cells mature

after antigen uptake, they migrate into the lymph nodes

mature cells present peptides, MHC complexes to CD4+ T helper cells, initiating adaptive immunity

what are naive T helper cells

mature t cell that has never encountered its specific antigen

what do macrophages and B cells require to upregulate MHC-II and co-stimulatory molecules

Activation signals

how is antigen uptake selective by semi pro APCs

Macrophages: phagocytose microbes and debris

B cells: internalize antigens specifically via their b cell receptor

what is the primary function of Semi pro APCs

to activate previously primed t helper cells

what are the functions of B cells

antigen recognition

antigen presentation

antibody presentation

meomory formation

cytokine secretion and immune regulation

what are the main functions of macrophages

pahgocytosis

antigen presentation

cytokine production

effector functions

bridge innate and adaptive immunity

what other cells can present an antigen

host infected cells and host tumor cells

present peptides fragments to cytotoxic T cells using MHC-1 molecules

what are histiocytosis and histiocytomas

disease caused by overgrowth of macrophages and dendritic cells

most common histiocytosis and histiocytomas

canine cutaneous histiocytosis

what is canine cutaneous histiocytosis

benign langerhans cell tumors that often resolve on its own but may sometimes spread

how do APC’s interact with MHC

antigen presenting cells must express MHC molecules and load peptides into the MHC binding groove for T cell recognition

what kind of MHC do vertebrates have

highly diverse MHc molecules

What specificity fo MHC molecules have

Broad specificity

each MHC molecule can bind many differetn peptides

what do MHC molecules dictate

whcih peptides are presented to T cells, shaping the T cell response

what does MHC specificity directly influence

genetic susceptibility or resistance to diseases where antigen presentation is critical

including infectious and autoimmune

what is the specificity of T cell receptors

exquisite specificity

each t cell expresses one unique TCR

what are the 2 types of MHC classes

MHC1- intracellular pathogens (viruses, some bacteria, tumor antigens)

MHC2- extracellular pathogens (bacteria, Parasites, toxins)

what does the origin of the pathogen depend on

which MHC pathway is used

what t cell subset does MHC1 activate

CD8+ cytotocix T cells

what t cell subsets does MHC 2 activate

CD4+ helper T cells

what is MHC2 expressed by

Professional APC and Semi professional

what is the peptide source of MH2

extracellular proteins taken up by endocytosis

what is the outcome of MHC2

provides cytokine help to both B cells and CD8+ T cells

essential for full b cell activation and antibody production

what is MHC1 expressed by

all nucleated host cells, including infected and tumor cells

what is the peptide source of MHC1

endogenous protiens synthesized inside the infected or transformed cell

what is the outcome of MHC1

activated CTLs to kill infected or abnormal cells

critical for antiviral and antitumor immunity

How do antigens enter the other MHC pathway

endogernous antigens into MHC2 pathway

exogenous antigens into MHC1 pathway

what is endogenous antigen entering into MHC2 via cell death

infected or tumor cells produce endogenous antigens normally presented on MHC1

when they are killed their microbial contents are released into extracell space

now extracell antigens can be phagoytosed by APCs and processed thru MHC2

what is exogenous antigens entering into MHC1 pathway by cross presentation

some extracell antigens can be diverted to MHC1, called cross presentation

Killed West Nile Virus Vaccine

explains why killed vaccines can still generate cell mediated immunity

why does MHC diversity matter for population survival

New pathogens bring new epitopes

why does high MHC heterogenecity cause an evolutionary advantage

Provides a survival advantage by ensuring that no single pathogen can wipe out all hosts

what is tasmanian devil facial tumor disease

type of tumor that has killed half the population

can spread between individuals

how are tasmanian devil cancer cells spread

physically during a bite, common during social interactions and mating

what happens when b cells become antibody producing plasma cells

usually need cytoking help from TH cells

to get help they need to present the antigen to Th cells

How is CTL effector cell activated

TcR binds the Ag/MHC1 on host infected cell

now can receiver cytokine help from activated Th cell