Question

When allograft grafts are in the recipient, and the tumor cell is in the body,

explain the similarities and differences between the implant and the tumor cell. (Immunologically)

How can i answer this??

Answer 1

Allotransplant is the transplantation of cell, tissue or organ from genetically non-identical donor. There are two types of tumours benign which do not spread and do not kill host. Whereas malignant tumour spread across the body of host and kill host.

Malignant tumours are considered as allograft because they contain tumour associated unique antigens on their cell surface, distinct from normal tissue antigen. The host recognise these antigens as non self and induce immune response.

Humoural response ( antibody mediated) donot play a major role to prevent tumour growth.

T cells play important role in graft rejection. However both cell mediated and humoural immune responses are associated with allograft rejection.

Both tumour and Allograft rejection is associated with immunologic memory.

NK cells and lymphokines kill tumour cells. Sensitised T cells kill the tumour cells.

Histocompatability antigens MHC or (HLA) are specific for each individual. During transplantation if there is mismatch in MHC then graft rejection by associated immune response will occur. If the grafted tissue or implant contain histocompatability Antigen which is absent in recepient, it will be consideted as foregin and rejected. In hyperacute rejection pre exsisting host antibodies react against the graft (complement activation, involvement of macrophage also occur). In acute rejection of implant, helper T cell mediate tissue damage ( CD 4, CD8, NK cells, Macrophages). Chronic rejection involve both cellular and humoural immunity.