[IIIIIIIIIIIIIII]

Antibodies are too large to pass through the filter in the kidneys. Lower molecular weight fragments of antibodies are usually reabsorbed in the proximal tubule of the nephron.

Their fate mostly lies in catabolism, i.e. they are broken down and the components reused. Biliary excretion accounts for a very small amount of the elimination of IgG antibodies.

[0] "Pharmacokinetics of Monoclonal Antibodies" http://onlinelibrary.wiley.com/doi/10.1002/psp4.12224/pdf

[robbiep]

Even if an antibody was eliminated, and managed to bind to an antigen, what good is it if it doesn’t have a complementary immune system to act on it

[IIIIIIIIIIIIIII]

Yes, that's actually the main point, thanks!

I missed it when I wrote my reply, concentrating on the immediate question (interesting psychological problem) - and then I could not edit it. It bothered me quite a bit but I did not want to write a third reply. Interesting to see how easy it is to get sidetracked on an irrelevant (albeit interesting) question, and how hard it is to get the discussion back on track.

[IIIIIIIIIIIIIII]

Shouldn't I be able to edit this for a little while? Strange, only two minutes later and I can't edit. It had no replies.

I tried adding this quote from the linked paper:

> Thus, IgG elimination occurs mostly through intracellular catabolism by lysosomal degradation to amino acids after uptake by either pinocytosis, an unspecific fluid phase endocytosis, or by a receptor-mediated endocytosis process.

Explanation of two words in there that maybe not everybody knows:

pinocytosis: The ingestion of liquid into a cell by the budding of small vesicles from the cell membrane.

endocytosis: The taking in of matter by a living cell by invagination of its membrane to form a vacuole.

EDIT: I can still edit this comment more than five minutes later, as expected. Hmm... why could I not do that with my first comment...?

[vanderZwan]

If this was your literal first comment, it could be some form of SPAM or trolling protection

[IIIIIIIIIIIIIII]

It was the 2nd comment, and since it's not been very long since the first one I remember that I edited it quite extensively, many times, for well over five minutes. This time I could start editing but could not (successfully) submit the edited text just two minutes after posting the comment, according to the time printed just above my comment after I submitted the edit (which only showed the text before the edit, and the "Edit" link was now gone).

[vanderZwan]

Then I don't know. You normally have around one hour to edit, IIRC.