57. Transplantation immunology. Relationship between donor and recipient. Host versus Graft (HvGR) and Graft versus Host reaction (GvHR).

Question 1

MHC molecules are used by cells of the immune system to distinguish foreign from self. They are markers of “self” . They also activate T lymphocytes, presenting antigens to antigen specific T cells. There are multiple types of transplantations, they are according to the nature of the transplant and according to the origin of the transplant. According to the nature there are organ, tissue and cell transplantations. According to the origin there are Auto, iso, alo and xenotransplantations. The histocompatibility antigens on tissues and cells determine their rejection when grafted between 2 genetically different individuals.

Answer 1

MHC molecules are used by cells of the immune system to distinguish foreign from self. They are markers of “self” . They also activate T lymphocytes, presenting antigens to antigen specific T cells. There are multiple types of transplantations, they are according to the nature of the transplant and according to the origin of the transplant. According to the nature there are organ, tissue and cell transplantations. According to the origin there are Auto, iso, alo and xenotransplantations. The histocompatibility antigens on tissues and cells determine their rejection when grafted between 2 genetically different individuals.

Question 2

HvGR - mechanism of rejecting is performed as a cellular immune response - MHC antigens initiate it. The antigens in the graft activate T-lymphocytes of the recipient. T-helpers play a major role in the mechanism of rejecting the graft - they activate

macrophages and T-cytollitic lymphocytes. Local inflammatory reaction occurs - thrombus are formed which block the blood vessels leading to necrosis and the graft is rejected.

Answer 2

HvGR - mechanism of rejecting is performed as a cellular immune response - MHC antigens initiate it. The antigens in the graft activate T-lymphocytes of the recipient. T-helpers play a major role in the mechanism of rejecting the graft - they activate

macrophages and T-cytollitic lymphocytes. Local inflammatory reaction occurs - thrombus are formed which block the blood vessels leading to necrosis and the graft is rejected.

Question 3

GvHR - Histoincompatible lymphoid cells when injected into an immunosuppressed host are readily accepted. Immunocompetent T lymphocytes found in the grafted cells recognise the alloantigens found on the host and proliferate and progressively cause damage to the host tissue and cells. Common manifestations: diarrhoea and weight loss.

Answer 3

GvHR - Histoincompatible lymphoid cells when injected into an immunosuppressed host are readily accepted. Immunocompetent T lymphocytes found in the grafted cells recognise the alloantigens found on the host and proliferate and progressively cause damage to the host tissue and cells. Common manifestations: diarrhoea and weight loss.

Question 4

Xenograft - between members of different species

Allograft - graft between members of same species

Isograft - graft between members of same species with identical genetic make up

Answer 4

Xenograft - between members of different species

Allograft - graft between members of same species

Isograft - graft between members of same species with identical genetic make up