Case Study 2: Mr. Smith is 52-yeaars old patient diagnosed 18 years ago with agg

Question

Case Study 2:

Mr. Smith is 52-yeaars old patient diagnosed 18 years ago with aggressive form of multiple sclerosis (MS). Back to the hospital, his doctor offer him one. Drug that will release steam cells from his bone marrow (collected from his blood), two. Antibodies against his T-lymphocytes. These procedures were offer to him in order to avoid problems such as transplant rejection.

Questions:

1.   What type of transplanted organ (aka graft) would it be if he receive someone bone marrow? On the other hand, what type of graft would be if he receive his own bone marrow?

2.   What are MHC proteins (class I or class II and what is the difference between the two classes)?

3.   The nurse explain to Mr. Smith that a bone marrow transplant from another donor could result in destroying his own immune cells. Provide your best explanation for this statement.

Explanation / Answer

Question 1.

Answer 1:

If a patient receives someone else's bone marrow for transplant from the same species, then it is called an allograft.

If a patient receives his own bone marrow for transplant then it is called an autograft.

Question 2:

Answer 2:

MHC or Major Histocompatibility Complex are cell surface proteins that bind to antigens and display them for recognition to antigen specific T cells. These molecules are responsible for tissue compatibility between individuals because they regulate T cell mediated immune responses.

The difference between MHC I and MHC II are as follows:

It is encoded by HLA-A, HLA-B and HLA-C.

(HLA stands for Human Leukocyte Antigen).

Question 3:

Answer 3

Transplants from another donor can destroy the receiver's own immune cells, which is called graft vs host disease. Patients who need bone marrow transplantation are generally immunocompromised and they receive a graft from an immunocompetent donor. What happens now is that the donor's immunocompetent T cells think that the recipient's HLA antigen are foreign and start reacting against them. So, the graft's T cells react against and destroy the recipient's immune cells. Thus, an allograft can lead to the destruction of the hosts' own immune cells. Also, this is why before a bone marrow transplant, HLA allele typing and matching is necessary, so that graft vs host disease is minimised.

MHC I MHC II It is expressed on all nucleated cells and platelets. It is only expressed on cells that present ingested antigens.

It is encoded by HLA-A, HLA-B and HLA-C.

(HLA stands for Human Leukocyte Antigen).

It is encoded by HLA-D. It is a hetermodimer with a polymorphic ? chain. It is a heterodimer with a ? chain and ? chain. It binds to and displays peptides that are derived from proteins, such as viral antigens. These antigens are usually produced in the cell. It binds to and displays antigens that are ingested into vesicles. These antigens are from extracellular microbes. Class I MHC and peptide complex is recognized by CD8+ T lymphocytes. Class II MHC and peptide complex is recognized by CD4+ T helper lymphocytes. It determines the histocompaitbility and the acceptance or the rejection of allografts. It regulates the immune response.

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