Date: Friday 23rd February
Time: 1pm – 2pm
Transplantation Immunity
Today we are going to finish the immunopathology lecture, yesterday we spoke about
immunity and hypersensitivity. Today we will finish this lecture, looking at transplantations.
Then we will cover a vevox and the responses from the mid-term evaluation. We will be
switching to medical microbiology in the next session.
Graft tissue taken from one site to another from the same person, this is called an autograph
as it is within the same body. If you have an identical twin giving skin, this is called an
isograph. Genetically non identical members of the same species are called allografts and are
rejected unless immunosuppressive therapy is given. Despite the ability to match recipients’
antigens (MHC class 1 and 2) we still need immunosuppressive therapy to stop rejection.
Between members of different species is called xenograft. This comes with ethical and
religious issues, along with rapid rejections to antibodies. This could also cause potential
problems such as pig disease.
The laws of transplantation in mouse model
1) Grey mouse (inbred) small skin taken from same species and haplotype skin is
accepted.
2) Brown mouse with different MHC molecules on grey mouse rejected.
3) Brown mouse skin given to an offspring between grey and brown accepted as
half of the haplotype is brown.
4) Grey x brown offspring brown mouse grey component will be recognised
leading to rejection.
Inherited immunodeficient diseases
These can be acquired or inherited. It can be a serious immunodeficiency such as combined
immunodeficiency due to the RAG genes joining to the receptors. 1/30000 children may have
this form of combined immunodeficiency.
Treatment = bone marrow transplant or disabled virus to get a working copy of defected
gene into the body.
Acquired immunodeficiency.
HIV virus – spike GP120 recognises CD4 on helper T cells, meaning the target for the
infection is the helper T cell. Because this is the orchestra of the immune response, helper t
cells work hard to overcome the virus, over time the CD4 helper t cells crash causing less
MHC, b cells etc which causes the immune system to shut down. Now very few people die
from this due to retroviral therapy.
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