Why does the body attack a transplanted organ? the organ has pathogens that the body wants to destroy. the organ is not recognized by the body as being made of self cells. the organ's ph level is not compatible with the recipient's ph level. the organ does not have enough nutrients to support the body.

The organ is not recognized by the body as being made of self cells.

Organ transplantation is a process in which an organ is transfer from a donor to a recipient, in order to compensate the loss occurring due to failure of organ in performing it's functions. Transplanted organ is attached or rejected by the immune system of the recipient. This happens because of the antigenic composition of the organ being transplanted is different from, the recipient. No two people except identical twins can have similar antigenic composition. For the recipient body the transplanted organ is like a foreign body, because of the antigenic dissimilarity. Hence, the organ is not recognized by the body as made of self cells and thus, the body attack a transplanted organ.  

The body attacks a transplanted organ because the organ is not recognized by the body and acts as a foreign particle.

Further Explanation:

Transplant rejection occurs in all nucleated cells, which possess MHC molecules on its surface. Successful organ or tissue transplants are possible only when there are similar MHC types in donor as well as the recipient. Allografts are tissues that are transplanted from one individual to another.

In the thymus, T-cell education takes place wherein the self-reactive T cells are eliminated by a negative selection process. The escaped T cells consist of T-cell receptors that do not identify the isogenic (genetically identical) MHC proteins on other body cells. Thus, the MHC protein of the donor rejects the different MHC types present in the recipient. This is known as transplant rejection. It is induced when the T-cell receptors of the recipient T-cell bind either directly to the foreign MHC of the donor cell or its pieces are processed and presented on the recipient cell. This causes T-cell activation. Activated cytotoxic T cells destroy all the donor cells comprising of allotypicMHC proteins, thus, rejecting it.

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Answer Details:

Grade: High School

Subject: Biology

Topic: Organ Transplant

Keywords:

Transplant rejection, t-cell, cytotoxic cell, MHC protein, rejects, identical, self-reactive, body cells, surface, organ transplantation, allograft, allotypic

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