Difference in immune response?

[oochygoochygoo]

Hi, I'm new here. I have a question and only basic background in science, so forgive me if this seems rather elementary, but I have not been able to find the answer through other means, so here I am... Hope I am not making a repeat thread - if this is the case I would appreciate someone sending me the link to the previous discussion. So this is my question -

 

Is there a difference in the human body's immune response when encountering an antigen that is injected intramuscularly versus an antigen that it encounters through normal means, as through the mucus membranes? If yes, what is the difference? How does this effect short and long term immunity to that particular antigen? Most obviously, this might be an antigen that one would encounter through vaccination rather than from human to human contact - but most vaccines are not live viruses, so is that an effect on long term immunity as well?

 

Any answer is greatly appreciated! Thank you!

 

Katie

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Also - I was told that the difference was that T1 cells are what initially encounters the pathogen when it enters the body in the usual way, whereas T2 cells are what initially encounter the pathogen when it is injected into the body, bypassing the body's other defenses, and that this is what effects long term immunity - for instance if you were to contract varicella virus from human to human contact T1 cells would encounter it first and after you are well you generally have life long immunity, but if you receive the varicella vaccine that T2 cells are what encounters the virus and your immunity is not as long term. Is this plausible, or is it more likely caused by the difference between the form of the virus that enters the body - live full strength virus vs. live attenuated virus?

[GDG]

Hi, I'm new here. I have a question and only basic background in science, so forgive me if this seems rather elementary, but I have not been able to find the answer through other means, so here I am... Hope I am not making a repeat thread - if this is the case I would appreciate someone sending me the link to the previous discussion. So this is my question -

 

Welcome

 

Is there a difference in the human body's immune response when encountering an antigen that is injected intramuscularly versus an antigen that it encounters through normal means, as through the mucus membranes? If yes, what is the difference? How does this effect short and long term immunity to that particular antigen? Most obviously, this might be an antigen that one would encounter through vaccination rather than from human to human contact - but most vaccines are not live viruses, so is that an effect on long term immunity as well?

 

Any answer is greatly appreciated! Thank you!

 

Yes, the method of administration has some effect on the body's immune response, although AFAIK the mechanism has not yet been nailed down. If you are exposed to an antigen via the mucous membranes (nose, sinuses, gut) you tend to develop more mucosal immunity (IgA). Otherwise, more systemic immunity (IgG). The memory cells will be essentially the same either way, so I don't think it has an effect on the duration of protection, just where the protection is focused.

 

Also - I was told that the difference was that T1 cells are what initially encounters the pathogen when it enters the body in the usual way, whereas T2 cells are what initially encounter the pathogen when it is injected into the body, bypassing the body's other defenses, and that this is what effects long term immunity - for instance if you were to contract varicella virus from human to human contact T1 cells would encounter it first and after you are well you generally have life long immunity, but if you receive the varicella vaccine that T2 cells are what encounters the virus and your immunity is not as long term. Is this plausible, or is it more likely caused by the difference between the form of the virus that enters the body - live full strength virus vs. live attenuated virus?

 

Actually, the T cells typically do not contact the antigens directly, but are usually presented by an APC (a "professional" antigen-presenting cell, such as a macrophage or dendritic cell). The T1 and T2 cells are usually called Th1 and Th2. Stimulation of Th1 cells tends to lead toward "normal" immune reactions, while stimulation of Th2 cells tends to lead toward allergy/asthma type reactions.

 

The sort of antigen does seem to make a difference as to whether Th1 or Th2 are activated, and this is still a subject of considerable research.

[oochygoochygoo]

Actually, the T cells typically do not contact the antigens directly, but are usually presented by an APC (a "professional" antigen-presenting cell, such as a macrophage or dendritic cell). The T1 and T2 cells are usually called Th1 and Th2. Stimulation of Th1 cells tends to lead toward "normal" immune reactions, while stimulation of Th2 cells tends to lead toward allergy/asthma type reactions.

 

The sort of antigen does seem to make a difference as to whether Th1 or Th2 are activated, and this is still a subject of considerable research.

 

Thank you so much! So do we really know what determines whether or not primarily TH1 or TH2 cells are stimulated? I guess the question would be is the method of introduction of the pathogen in question - through mucous membranes or intramuscular injection - the deciding factor?

 

Also, some are saying that consistent stimulation of the TH2 cells instead of TH1 cells (through multiple vaccinations at an early age) can throw the immune system off balance and cause autoimmune disorders/allergy issues because the body learns to respond to pathogens using the TH2 cells. Does that have any sort of validity?

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Okay, I just reread your response a few times. Sorry if I'm asking you the same questions over again in different ways...

 

It sounds to me like we still are unsure what exactly triggers either TH1 or TH2 cells to respond to specific pathogens - the type of pathogen could have something to do with it, as well as the method of introduction. Am I right there?

 

I could come up with more questions all day, it seems one just leads to the next!

[GDG]

Thank you so much! So do we really know what determines whether or not primarily TH1 or TH2 cells are stimulated? I guess the question would be is the method of introduction of the pathogen in question - through mucous membranes or intramuscular injection - the deciding factor?

 

Also, some are saying that consistent stimulation of the TH2 cells instead of TH1 cells (through multiple vaccinations at an early age) can throw the immune system off balance and cause autoimmune disorders/allergy issues because the body learns to respond to pathogens using the TH2 cells. Does that have any sort of validity?

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Merged post follows:

Consecutive posts merged

Okay, I just reread your response a few times. Sorry if I'm asking you the same questions over again in different ways...

 

It sounds to me like we still are unsure what exactly triggers either TH1 or TH2 cells to respond to specific pathogens - the type of pathogen could have something to do with it, as well as the method of introduction. Am I right there?

 

I could come up with more questions all day, it seems one just leads to the next!

 

No problem

 

If we knew exactly how the system worked, it would be much easier to design effective vaccines. In general, we try to avoid activating the Th2/allergy branch. I don't think that commercial vaccines (in general) do activate Th2, because you would not get a protective response. The Th2 response seems to be geared toward fighting off parasites, like flukes and worms, rather than bacteria and viruses. And yes, antigens associated with such parasites do tend to activate Th2, but (AFAIK) we are not yet sure just what characteristics of those antigens tips the scale in the Th2 direction. It is known that there are a number of interleukins involved (I don't remember off hand which combinations).

 

One of the current theories to explain increasing autoimmune and allergy disorders is called the "hygiene hypothesis". Basically, the hypothesis is that us modern citizens are too clean, and the lack of immune system exercise on parasites, etc., leads it to attacking normal tissue.