Antibody therapies immunosuppression

Induction—Administration of a highly intense level of immunosuppression in the perioperative period or use of antibody therapy to provide enough immunosuppression to delay administration of nephrotoxic calcineurin inhibitors. 

Later we shall review the extensive literature that exists for monoclonal antibody therapy in animal models both as immunosuppressants and agents to induce antigen-spedfic immunological tolerance and yet, as already stated, only mAbs to CDS and CD25 (IL-2 receptor) are licensed for transplantation in humans. These two targets for therapy may not even be the best choices based on experimental data, so why have they had such relative success ... 

CMV may be transmitted to the seronegative recipient by a seropositive donor or CMV can reactivate in the seropositive recipient as the result of immunosuppression especially if anti-lymphocyte antibody therapy is employed (Rubin 2000). Ganciclovir is the first-line treatment for CMV infections, but resistant strains may require additional drugs. 

Jaffers GJ, Fuller TC, Cosimi AB, Russell PS, Winn HJ, Colvin RB. Monoclonal antibody therapy. Anti-idiotypic and non-anti-idiotypic antibodies to OKT3 arising despite intense immunosuppression. Transplantation 1986 41 572—578. 

Nonspecific immunosuppressive therapy in an adult patient is usually through cyclosporin (35), started intravenously at the time of transplantation, and given orally once feeding is tolerated. Typically, methylprednisone is started also at the time of transplantation, then reduced to a maintenance dose. A athioprine (31) may also be used in conjunction with the prednisone to achieve adequate immunosuppression. Whereas the objective of immunosuppression is to protect the transplant, general or excessive immunosuppression may lead to undesirable compHcations, eg, opportunistic infections and potential malignancies. These adverse effects could be avoided if selective immunosuppression could be achieved. Suspected rejection episodes are treated with intravenous corticosteroids. Steroid-resistant rejection may be treated with monoclonal antibodies (78,79) such as Muromonab-CD3, specific for the T3-receptor on human T-ceUs. Alternatively, antithymocyte globulin (ATG) may be used against both B- and T-ceUs. 

The improved short-term outcomes gained from induction therapy come with a degree of risk. By using these highly immunosuppressive agents, particularly the antilymphocyte antibodies (ALAs), muronomab-CD3 (OKT-3), and the antithymocyte antibodies, the body loses much of its innate ability to mount a cell-mediated immune response, which increases the risk of opportunistic infections and cancer.7,10... 

Antibodies have and likely will find additional use in transplantation-related medicine. In general, cell-mediated immunological mechanisms are responsible for mediating rejection of transplanted organs. In many instances, transplant patients must be maintained on immunosuppressive drugs (e.g. some steroids and, often, the fungal metabolite cyclosporine). However, complications may arise if a rejection episode is encountered that proves unresponsive to standard immunosuppressive therapy. Orthoclone OKT-3 was the first monoclonal antibody-based product to find application in this regard. 

The major types of drug therapy used in IBD include aminosalicylates, glucocorticoids, immunosuppressive agents (azathioprine, mercaptopu-rine, cyclosporine, and methotrexate), antimicrobials (metronidazole and ciprofloxacin), and agents to inhibit tumor necrosis factor-a (TNF-a) (anti-TNF-a antibodies). 

Immunosuppression During therapy, do not use live virus vaccines (eg, smallpox). Do not immunize patients who are receiving corticosteroids, especially high doses, because of possible hazards of neurological complications and a lack of antibody response. This does not apply to patients receiving corticosteroids as replacement therapy. 

The present primary mode of therapy for these diseases involves the use 5-amino-salicylate (5-ASA) products. Often patients require additional medications, including corticosteroids, to help induce remission and various immune modulators, such as azathioprine, 6-mercaptopurine or methotrexate, to maintain remission. In Crohn s disease certain antibiotics, such as metronidazole and ciprofloxacin, and infliximab Remi-cade), an anti-tumor necrosis factor-a(TNFa) antibody, also have been used. The pharmacology of antibiotics, immunosuppressive drugs, and corticosteroids is discussed in Chapters 43,57, and 60, respectively. 

The effectiveness of immunosuppressive drugs in autoimmune disorders varies widely. Nonetheless, with immunosuppressive therapy, remissions can be obtained in many instances of autoimmune hemolytic anemia, idiopathic thrombocytopenic purpura, type 1 diabetes, Hashimoto s thyroiditis, and temporal arteritis. Improvement is also often seen in patients with systemic lupus erythematosus, acute glomerulonephritis, acquired factor VIII inhibitors (antibodies), rheumatoid arthritis, inflammatory myopathy, scleroderma, and certain other autoimmune states. 

Immunosuppressive therapy is utilized in chronic severe asthma, where cyclosporine is often effective and sirolimus is another alternative. Omalizumab (anti-IgE antibody) has recently been approved for the treatment of severe asthma (see previous section). Tacrolimus is currently under clinical investigation for the management of autoimmune chronic active hepatitis and of multiple sclerosis, where IFN-3 has a definitive role. 

Muromonoab-CD3 is used for the treatment of acute organ transplant rejection. It is effective in preventing graft rejection after kidney, heart or liver transplantation. Muromonoab-CD3 is effective in patients who after acute cardiac or liver allograft rejection do not respond to steroid therapy. It is administered intravenously and with a dose of 5 mg/day, a general concentration range of 400-1500 ng/ml can be achieved. A serum concentration of 600-1150 ng/ml in renal transplant patients produces desirable immunosuppressive effects. The levels of CD3 expression, their production and antibodies to the drug determine its rate of clearance. In the absence of antibodies to muromonoab-CD3, its half-life is about 18 h. 

Statin-induced lupus-like syndrome is characterized by a long delay between the start of therapy and the skin eruption. Antinuclear antibodies can persist for many months after drug withdrawal. The causal relation may be therefore difficult to establish, and probably many cases are unrecognized. Early diagnosis may avoid unnecessary immunosuppressive therapy. 

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