Lecture 19 - B lymphocytes and antibodies Flashcards Preview

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Flashcards in Lecture 19 - B lymphocytes and antibodies Deck (11):
1

Cytokines

-small glycoprotein messenger molecules and attatch to receptors on other cells to cause effect

2

Interleukin
interferon
CSF

interleukin - between leykocytes
interferon - interferes w viral replicaiton
CSF - colony stimulating factor

3

Interferons IFNa, b, y (innate)

inhibits viral infections
are innate cytokines
2 ways
-as virus starts to replicate in a cell, these cytokines are produced
1. these bind to receptors on cells close to the infected cells, and these cause changes in gene expression to make new proteins - virally infected cells can now be more protected before they get infected
2. affects leukocytes in our blood called natural killer cells - these up regulate the ability to recognise changes associated with infection and will go on to kill those cells before they infect other cell s

4

IL-1, IL-6, TNF-a
(innate cytokines)

pro inflammatory cytokines
-wound healing and tissue repair
-fibroblast proliferation
-bone resorption
-prostaglandin and collagenase synthesis
-neuroendocrine effects

5

Adaptive cytokines

IL-1 - t and b cell activation

IL2 - t cell proliferation, nk cell activaiton

IFN-y - antiviral , macrophage activation, NK cell activation, MHC upregulation

IL-4, 5, 6 - b cell differentiation , antibody class switching

6

Chemokines

IL-8 - neutrophil migration

MCP-1, MIP-1a - C-C motif, allergic inflammation

7

Infant failing to thrive

-can do a test on antibody levels
-may develop recurrent infections
-why does baby have no tonsils? - maybe very few b cells, and tonsils are a secondary lymphoid organ where alot of b cells are
-good for the first 10 months due to mothers acquired immunity
-can supplement baby with things that they cannot make - passive immunity

8

graph of antibodies

fdsfd

9

B cell clonal activation

-has receptors specific for an antigen
-if matches with a correct antigen will digest this, and then present it on mhc 2
-a t helper cell with same antigen recognition will give the go ahead if there is costimulation
-then the b cell will become activated and make antibodies against this antigen
-and then the b cell will also make memory b cells incase it gets this antigen later on in life

10

Antibody effects

Blocking an neutralisation
-attachment and entry (viruses, parasites)
-Main protective effect of secretory igA
-toxins
-immobilising bacterial flagella

Agglutination - clumping to assist phagocytosis (especially igM) - size depends on saturation of antibody

Opsonisation

Antibody dependent cellular cytotoxicity (antibody can link the large granular leukocyte to tumour cell, and then get granules released to destroy)

Complement activation (antibodies bind to bacteria, this results in complement proteins becoming activated to form an enzyme, this goes on to cleave C3, and activates it C3a - affects blood vessel permeability, and C3b fragment - covalently attaches to anything nearby - this is a link to phagocytic cells so enhances phagocytosis/opsoinaation, also activates further complement cascade which results in C5a which causes chemotaxis, but also organises the late components which insert itself into the membrane of what it is attached to and kills it) -this punches a while in membrane, and can breach its integrity

11

2 ways complement is activated

1.cell wall components of bacteria
2. Antibodies bound to antigen