rejection (redirected from rejection factors)

rejection /re·jec·tion/ (re-jek´shun) an immune reaction against grafted tissue that results in failure of the graft to survive.

---

re·jec·tion (r-jkshn)

n.

1. The act of rejecting or the state of being rejected.

2. The failure of a recipient's body to accept a transplanted tissue or organ as the result of immunological incompatability; immunological resistance to foreign tissue.

---

Rejection

Rejection occurs when the body recognizes a new transplanted organ as "foreign" and turns on the immune system of the body.

Mentioned in: Immunosuppressant Drugs, Kidney Transplantation

---

rejection

[rijek′shən]

Etymology: L, re + jacere, to throw

1 an immunologic attack against organisms or substances that the immune system recognizes as foreign, including grafts and transplants. See also acute rejection, chronic rejection.

2 the act of excluding or denying affection to another person.

---

rejection [re-jek´shun]

the immune response of the recipient to foreign tissue cells (antigens) after homograft transplantation, with the production of antibodies and ultimate destruction of the transplanted organ. In hyperacute rejection, there is an immediate response against the graft because of the presence of preformed antibody, resulting in fibrin deposition, platelet aggregation, and neutrophilic infiltration. In acute rejection, the response occurs after the sixth day and then proceeds rapidly. It is characterized by loss of function of the transplanted organ and by pain and swelling, with leukocytosis and thrombocytopenia. In chronic rejection, there is gradual progressive loss of function of the transplanted organ with less severe symptoms than in the acute form.

---

rejection

the immune reaction of a recipient to a graft, usually an allograph, after transplantation. The recipient recognizes antigens, particularly major histocompatibility complex antigens that are different from self antigens. The rapidity and severity of the graft rejection parallels the degree of antigenic difference between donor and recipient. The primary rejection of a graft, called first set reaction, typically begins 6 to 10 days after engraftment and in the case of skin is characterized by an erythematous zone around the graft which subsequently shrinks and is rejected. Rejection is predominantly a cell-mediated immune response, particularly Th1 lymphocytes and activated macrophages. If the same recipient receives a second graft from the same donor the graft is rejected more rapidly and the response is more severe, called a second set reaction which is also a cell-mediated response. Lymphocytes from the recipient can be adoptively transferred to a naive recipient which if also given a graft from the same donor responds with a second set reaction.

---

rejection factors

antibodies, particularly IgM but also IgG, directed against antigenic determinants on the Fc region of other immunoglobulins. When the immunoglobulin binds to antigen, changes occur in the folding of the protein of the Fc region such that new, nonself antigenic determinants are exposed and it is to these that rheumatoid factors, i.e. other antibodies, are directed.

---

rejection

Immunology An immune reaction evoked by allografted organs; the prototypic rejection occurs in renal transplantation, which is subdivided into three clinicopathologic stages. See Cyclosporin A, Graft rejection, Graft-versus-host disease, Second set rejection, Tacrolimus, Transplant rejection.

Rejection types  

Hyperacute rejection Onset within minutes of anastomosis of blood supply, which is caused by circulating immune complexes; the kidneys are soft, cyanotic with stasis of blood in the glomerular capillaries, segmental thrombosis, necrosis, fibrin thrombi in glomerular tufts, interstitial hemorrhage, leukocytosis and sludging of PMNs and platelets, erythrocyte stasis, mesangial cell swelling, deposition of IgG, IgM, C3 in arterial walls

Acute rejection Onset 2-60 days after transplantation, with interstitial vascular endothelial cell swelling, interstitial accumulation of lymphocytes, plasma cells, immunoblasts, macrophages, neutrophils; tubular separation with edema/necrosis of tubular epithelium; swelling and vacuolization of the endothelial cells, vascular edema, bleeding and inflammation, renal tubular necrosis, sclerosed glomeruli, tubular 'thyroidization' Clinical ↓ Creatinine clearance, malaise, fever, HTN, oliguria

Chronic rejection Onset is late–often more than 60 days after transplantation, and frequently accompanied by acute changes superimposed, increased mesangial cells with myointimal proliferation and crescent formation; mesangioproliferative glomerulonephritis, and interstitial fibrosis; there is in general a poor response to corticosteroids