Does the Rhesus factor thingo at birth count as an allergic response as parents aren't supposed to react to their babies?
If so, this occurs much more intensely upon having another baby, so if this were an allergy (pending confirmation) then this is a good example to answer the above question
Very interesting q!
However, I wouldn't think that would be the case. People who can't donate blood to other people are not said to be allergic to other people because they can't accept blood from them. They simply do not have the specific antigens in their own blood for the successful transfer to occur. True, allergic responses are by particles or substances that do not usually cause an immune response, such as nuts etc, but blood that cannot transfer from Person A to Person B is probably considered a normal thing.
This is a really pertinent question to VCE, because allergy is a subtle thing. Hydroxyl, you're quite right and your example is a good one. Although, it is worth saying that blood from the wrong host does generate an immune response (called a blood transfusion reaction). For instance, giving B blood to an A blood type person is extremely dangerous and will cause a potentially fatal immune response.
Allergy is not simply an immune response to something foreign. It's a specific type of immune response that involves IgE and the release of small molecule factors, such as histamine. So it is possible to react to potentially immunogenic substances in other ways that is not considered an allergy, for instance, blood transfusion reaction. Another example is coeliac disease, which is an immune response directed to a foreign substance (gluten) that some do consider an allergy, but in reality probably isn't because of the way the immune system reacts to it.
A question to do with adaptive immunity, specifically cell-mediated immunity. I'm a bit confused so apologies if this is a silly question.
Why is it that cytotoxic T cells do not kill APCs if APCs have the foreign antigen presented on their surface?
Good question.
APCs present their antigen in the context of MHC class II, whereas cytotoxic T-cells can only respond to antigen presented on MHC class I