So, I just had 4 units of whole blood tranfused into me. (I am O+) Someone pointed out that I am also the likely recipient of some antibodies my donors might have. Does this mean that, if one of those donors had, like, a cold in their past, that I now have antibodies protecting me from that cold virus? What about other antibodies? Conceptually, am I metabolically "distinct" from who I was last week? Does that kind of thing show up in tests, at least theoretically? i.e. can a future test indicate that I might have had a transfusion in my history?