I have donated blood for years and never have even been asked about my AS. I disclose it on the questionnaire you have to fill out but its never stopped me from donating. I also donate platelets.
Lot of paperwork never gets looked at... I would discuss it with someone personally prior to donating.
When I lived in Neenah, Wisconsin and our company had a blood drive, I asked if I could donate and informed them of medications I was taking and that I had AS. They told me at the blood drive (circa 1998) I could NOT donate.
Tim