Blood contains antibodies to the other blood types where on earth do antibodies come from if body is not exposed 2 dem?
It turns out that you don't enjoy to be exposed to something to have an antibody to it. One of the planning of antibody formation is that, when you are developing, your body makes antibodies against almost everything. So, during nouns, if an antibody sticks to part of you, that antibody (and the cell that produces that antibody) is removed from the body. Through this process, your body removes any antibody-producing cell that might attack your body. So, after your immune system finishes developing, what you have gone is a lot of cell that can produce antibodies against things you haven't been exposed to even so, and all of the cell that produce antibodies against self have be removed. This system provides you with self-recognition (you own no antibodies against yourself) and foreign body recognition (the antibodies you manufacture are all against things foreign to your body).
So, surrounded by the case you mention, you wouldn't hold any antibodies against blood type A antigen, but would have antibodies against blood type B antigen.
Antigens against which the body produces antibodies are not other unique. Blood group B antigens may be duplicate antigens as those present on milk proteins that the baby get in his food. Or these antigens may be duplicate as those present on bacteria that are a cut of the normal flora within the intestine.
When you are exposed to environmental antigens that your body also has. Then your body does not produce any antibodies against these antigens. But when the environmental antigens are different from those contained by your body. Then your body does produce antibodies against them.
There are two types of antibodies in our body: one type is present from the birth, while other type is acquire as a result of the exposure to the antigens from the external environment. Antibodies to blood antigens are present since birth. As our blood group is determined by the genes of our parents, so are these antibodies. Hence, they are there even if we are not exposed to the external antigens.