B & T cells-interaction, mechanisms (1 Viewer)

[~Loz~]

The interaction between B & T Lymphocytes-
§[FONT=&quot] [/FONT]Firstly, the antigen travels in the blood until it is engulfed by a macrophage
§[FONT=&quot] [/FONT]The macrophage then becomes an antigen-presenting cell - it displays the antigen it has engulfed on its surface.
§[FONT=&quot] [/FONT]The macrophage then ‘alerts’ the immune system to the presence of large numbers of antigens in the body by presenting the antigen to a Helper T-Cell.
§[FONT=&quot] [/FONT]The Helper T-Cells then produce the chemical INTERLEUKIN, which stimulates T and B-Cells to differentiate into their different types
§[FONT=&quot] [/FONT]NOTE: The B and T-Cells can be activated either by Helper T-Cells, like above, or activated directly by antigens. Both processes have the same result:
Ø[FONT=&quot] [/FONT]The T-Cells are also activated by infected cells displaying the antigens
Ø[FONT=&quot] [/FONT]The B-Cells are also activated by free antigens in the blood.
§[FONT=&quot] [/FONT]The T-Cells differentiate into Killer (cytotoxic) T-Cells, Memory T-Cells and Suppressor T-Cells.
§[FONT=&quot] [/FONT]The B-Cells differentiate into Plasma B-Cells and Memory B-Cells
[FONT=&quot]The Plasma B-Cells then destroy the antigen by secreting antibodies, and the Cytotoxic T-Cells also destroy the antigen
IS THIS CORRECT/ANYTHING ELSE I NEED TO ADD FOR THIS DOTPOINT

the mechanisms tht allow interaction between B & T Lymphocytes-
[/FONT] §[FONT=&quot] [/FONT]Clonal Selection:
Ø[FONT=&quot] [/FONT]This is the work of MacFarlane Burnett
Ø[FONT=&quot] [/FONT]Before an antigen enters the body, there are already many types of lymphocytes in the body
Ø[FONT=&quot] [/FONT]The entry of an antigen causes the selection of only ONE of the types of lymphocyte – the one that has the binding site which matches the antigen
Ø[FONT=&quot] [/FONT]This results in this lymphocyte cloning itself into large numbers of this same lymphocyte, so it produces the antibody that matches the antigen
Ø[FONT=&quot] [/FONT]This selection means that all the lymphocytes that are produced in the response (all the T and B Cells) are all specific ONLY to that antigen
Ø[FONT=&quot] [/FONT]This means that, for example, the Cytotoxic T-Cells for influenza bacteria cannot kill the pneumonia bacteria
Ø[FONT=&quot] [/FONT]Macrophages engulf and kill all foreign cells – lymphocytes only act against the antigens that they specifically match.
§[FONT=&quot] [/FONT]Cytokines and Interleukins:
Ø[FONT=&quot] [/FONT]Cytokines are a group of SIGNALLING COMPOUNDS made of proteins or polysaccharides that are used for communication between cells
Ø[FONT=&quot] [/FONT]They coordinate the functions of cells so that they can act together as a whole, such as in the immune response
Ø[FONT=&quot] [/FONT]Interleukins are a type of cytokine that are secreted by Helper T-Cells and the macrophages
Ø[FONT=&quot] [/FONT]When these cells secrete interleukins, they are signalling, or stimulating, the other cells to differentiate, in response to an antigen – such as a B-Cell changing into a Plasma B-Cell
Ø[FONT=&quot] [/FONT]This is the main mechanism that is used for intercellular interaction



IS THIS CORRECT/WOULD I NEED TO ADD ANYTHING??????
HELP IS GREATLY APPRECIATED!!!!!!!
iS THERE ANYWAY TO ALSO SIMPLIFY ALL THIS INFO SO THT IT IS EASY TO UNDERSTAND & TO REMEMBER!!!!!!????!!!!!

 

[Survivor39]

Interleukins are secreted by all kinds of cells, not just Helper T cells and macrophages. e.g. neutrophils also secrete interluekins, so do cytotoxic T cells (CD8 T cells), intestinal epithalial cells etc.

 

[eddy11]

[FONT=&quot] and the Cytotoxic T-Cells also destroy the antigen
[/FONT]

I think the Cytotoxic T-Cells destroy the actual cells that are displaying the antigen on their surface, they do this by releasing perforin (perforate=to make hole in) which basically makes the cell pop, cell dies and so does pathogen relying on cell, or at least thats the plan...

i hope that helps/is correct, otherwise it looks good to me, thanks for posting it up i wanted a nice little summary like that, well done, cheers

 

[katie tully]

^ Yes above is correct. Rather than just killing the antigen, killer T cells destroy the entire cell.

 

[Survivor39]

I think the Cytotoxic T-Cells destroy the actual cells that are displaying the antigen on their surface, they do this by releasing perforin (perforate=to make hole in) which basically makes the cell pop, cell dies and so does pathogen relying on cell, or at least thats the plan...

Well done for pointing that out!

If you are interested, the entire process of Cytotoxic T cell killing is, as you would expect, much more complex but extremely interesting. In simple terms, the Cytotoxic T cells release not only perforin, but granzyme, onto the surface of the target cell via the immunological synapse formed between the T cell and the target cell. This synapse is sealed as to prevent diffusion of these enzymes into the surrounding environment. You are also correct in saying that the perforins form holes on the membrane of the target cell. However, forming holes doesn't make the cell "pop" as such, but to allow granzyme to enter the target cell. The granzyme is a deadly activator of apoptosis, or programmed cell death. The mechanism of apoptosis is initiated by triggering a series of cascade of proteins which leads to fragmentation of target cell DNA and eventual cell death.

 

[Kujah]

Whats the difference between apoptosis and necrosis?

 

[katie tully]

Not an indepth answer for you, but apoptosis is the programmed death of a cell, where as necrosis is an unnatural death of a cell.

 

[obiman]

why the hell u need to know that?

 

[Survivor39]

Whats the difference between apoptosis and necrosis?

Yes, like what katie has said. Apoptosis is programmed, and therefore controlled and can be activated by extrinsic (external) or intrinsic (internal) signals. Apoptotic cells generally do not lyse but they fragment and degrade into small pieces. No inflammation is induced.

Necrosis is cell death via injury, such as cell death from exposure to chemicals or radiation, or death by physical injury. Necrosis results in cell lysis and inflammation.

 

[eddy11]

why the hell u need to know that?

you dont, a well developed understanding of the immune response for the HSC is actually a relatively basic understanding. If you look at most HSC text books, it doesnt seem to complicated or interesting, but it is!

EDIT: the trick with this topic is not trying to learn to much, the markers are looking for a basic understanding, looking into it to far often confuses you because extra things you find out conflict with what you've learnt. The best thing to get out of this thread is the OP's summary. All the extra bits are not important for your HSC, their just interesting to know about.

 

[katie tully]

Basically, if you want to be a band 6 student in Biology, you need to go above and beyond whats in the text book. It's expected of you as a top student in science not just to rely on the text.

If you're learning about B & T cells for example, and do some independent research, you'll find the topic a lot easier to understand and you'll be able to bulk up your answers more.

I think we all know the difference between a band 6 and a band 3 answer in Bio?

 

[eddy11]

Basically, if you want to be a band 6 student in Biology, you need to go above and beyond whats in the text book. It's expected of you as a top student in science not just to rely on the text.

If you're learning about B & T cells for example, and do some independent research, you'll find the topic a lot easier to understand and you'll be able to bulk up your answers more.

I think we all know the difference between a band 6 and a band 3 answer in Bio?

yeh good point but i that its possible for some students to go a bit further then they need or are capable of, which may lead to them panicing and concentrating on this one topic too much.

 

[katie tully]

Probably too late for the class of 08, but I might devise a thread with some study hints for Biology for the 09ers.

There are definitely some tricks us old hats can pass on, and really I don't think anybody should freak out over Bio. It's a great subject, and although it might appear that there is a lot to learn, a lot of it is intertwined.

But I will do that today. Post up a study hint thread that others can contribute to.

 

[eddy11]

good idea, oh and even though people shouldnt stress about bio, they do

 

[omegasparkle]

1. simplifyied b+t lymphocytes- all u really need 2 know
2. specific immunity

 

[Flop21]

For the mechanisms... would describing just the cytokines and interleukins be okay instead of the cloning?