Newbie87, Yes, antibodies can take a while to show up in blood tests. No, they don't know "why."
In 2000, my modulating antibody was 18%, below normal (0-19 range). In 2002, it was 23%, above normal.
Mestinon has been shown (in one study only) to suppress the humoral immune system that produces antibodies, so having a blood test while on it "may" effect the results.
Antibodies can circulate in the blood or be "tissue bound." I mean, they go and attack tissues for a living.
I have not read any good articles on why some circulate and why some stay in the area they are attacking. I'm sure there is something out there on that. So if they are not circulating, they wouldn't show up in the blood.
I hope a thymectomy works for you. It may or may not. I wish my life were "normal" too.
Annie