adaptive immunity

adaptive immunity cells

CD4 TH cells, CD8 cytotoxic T cells, B cells, lymphocytes

lymphocytes - types and development

T and B - short lifespan, activated by antigen, both originate in the bone marrow, B cells mature there, T cells mature in thymus

how do immune cells and pathogens find each other

interstital fluid enters lymphatic vessels with blood vessels, within lymph nodes pathogens and particles find and activate APCs

primary lymphoid organs

bone marrow & thymus

secondary lymphoid organs

spleen and lymph nodes

how do lymph nodes function

they contain different zones of immune cells, APCs present antigens to B and T cells in lymph nodes

spleen function and sections

blood filter, red pulp, white pulp, germinal centre

red pulp

removes old RBCs

white pulp

contains lymphocytes (B+T) and macrophages

germinal centre

rapid B cell proliferation for fast antibody production

APCs include ..

dendritic cells - best at activating naive T cells, macrophages, B cells

how do B cells mature

in bone marrow - self reactive B cells are destroyed

stages in humoral response

receptor interacts with pathogen directly, plasma and memory B cells are produced, plasma cells produce antibodies

humoral response defends against …

pathogens and toxins in extracellular fluid

cell mediated response defends against ..

infected cells, cancer cells, transplanted cells

T cell selection processes

positive selection - selected if they can become activated by APCs. negative selection - die if they recognise self too strongly, to prevent autoimmunity

cell mediated response steps

cytotoxic (CTL) activated by presented antigen from infected cell, active CTL and memory CTLs produced, TH cell activated by antigen, produced active TH and memory TH cells

IgM

first antibody produced in response, pentameric

IgE

allergic reactions

IgD

membrane bound

IgA

secretion into mucosal linings

IgG

highest amount of antibody produced

antigen def

a foreign molecule which is specifically recognised by lymphocytes and elicits a response from them

epitope

antigenic determinant

MHC1

protein which all nucleated cells in the body have in CSM

allows antigen to be held

TH1 cells

for inflammatory infections

TH2 cells

type 2 infections - helminths and allergies

TH17

fungal and inflammatory skin infections

T regulatory cells

turns off response