Immuno pimp question

[hcrunner82]

Hey, hoping someone can help me out with this question I got pimped on today during peds rounds...i'll apologize in advance if this is a dumb question but immuno was not my strong point on step I and i want to do neurology anyway

Can anyone explain(or post a link since I can't find the answer anywhere) the time frame of when both IgM and IgG will peak and start to decline during an infection? My patient had a reactive IgM for myco and all I could remember was that IgM could stay positive for 6months to a year.

Specifically my attending wanted to know
-when does IgM reach its peak and then decline?
-when does IgG start to rise? When does IgG reach its peak and start to decline?

Thanks for any help, I have until Monday morning to find this out

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[Ypo.]

You know, I think it depends on the infection and the antigens involved. I would imagine that not all infections follow the same course. Was your attending asking about a specific disease?

I think I remember that IgG takes at least a month to form whereas IgM is immediate. But the immune response mounted is going to depend on the antigen load and type of antigen. Ie-some thymus independant antigens don't require T-cells to make Ig, so you can get both IgM and IgG immediately (for example the flagella of Salmonella carries such an antigen as does the capsule of pneumococcus).

 

[yaah]

You can find lots of graphs on google. Short answer is that it's different for every response. IgM usually peaks in a couple of weeks then falls off. IgG gradually rises, peaks later. Either one can stay positive forever or disappear and only reappear on rechallenge/reexposure of the antigen.