Question about primary immune response

[adityar]

Suppose a bacterium was accidentally injected into someone's bloodstream. This bacterium has antigens the body has never seen before, and so there are no B cells to counter it. What happens? Are new antibodies synthesised, and if so, how?

 

[NouranAyman]

Macrophages cut the pathogen displaying its antigen, then T lymphocytes with the suitable receptor will bind with the antigen and divide by mitosis and relase the hormone like substance called cytokines that stimulate the B lymphocytes to divide, also T killer cells can produce toxic substances to kill the antigen, and produce cytokine interferon which stops viral replication,. This is a primary immune response, its not necessary that the antigen should have attacked the body before for the response to take place, New antibodies and memory cells are formed to have a quicker response if the antigen is reintroduced to the body again.

 

[anwar2400]

Suppose a bacterium was accidentally injected into someone's bloodstream. This bacterium has antigens the body has never seen before, and so there are no B cells to counter it. What happens? Are new antibodies synthesised, and if so, how?

the probability of that happening is very low
but if that happens then i dont think that antibodies will be produced as B cells are not stimulated

 

[adityar]

the probability of that happening is very low
but if that happens then i dont think that antibodies will be produced as B cells are not stimulated

Yeah, I was thinking that too, but I can't help but imagine, in some books it says that antigenic shift occurs very frequently in some bacteria, even every 5 days, so the immune system must have that "if no antibody can be found" thing, otherwise, the system would not be as efficient...

 

[TCHS]

Wouldn't this invasion of a foreign particle at first stimulate phagocytes to engulf it & if it is too big, then stimulate B cells to divide into Plasma cells (which will secrete antibodies) & memory cells?

 

[anwar2400]

Yeah, I was thinking that too, but I can't help but imagine, in some books it says that antigenic shift occurs very frequently in some bacteria, even every 5 days, so the immune system must have that "if no antibody can be found" thing, otherwise, the system would not be as efficient...

you are right that is why we get common colds, they are from adenoviruses
they change their antigens every now and then
since there are 122 types of common colds and untold number to changing antigens, you are most likely to catch a cold from an infected person, because you dont have the necessary receptors on the B cells