One hundred and seventeen of 270 (43%) recipients of organs obtained from donors with malignancies had evidence of transmitted cancers. In 9 instances these were removed from renal allografts immediately prior to transplantation. Including these cases there were 45 recipients of organs in which a neoplasm involved the allograft, 6 others in whom adjacent structures were invaded, and another 66 patients who had distant metastases. Precautions to prevent cancer transmission include meticulous preoperative screening of donors, careful examination of all organs at the time of harvesting, biopsy of any suspicious lesions, and routine donor autopsy, if possible.
PTLD may be considered as an "opportunistic cancer" in which the immunodeficiency state of the host plays a key role in fostering the environment necessary for abnormal lymphoproliferation. The following discussion reflects our own current thoughts regarding events which may result in PTLD and its sequelae. Many of the individual steps have not been rigorously proved or disproved at this point in time. Following transplantation and iatrogenic immunosuppression, the host:EBV equilibrium is shifted in favor of the virus. Most seronegative patients will become infected either via the graft or through natural means; seropositive patients will begin to shed higher levels of virus and may become secondarily superinfected via the graft. There is a "grace" period of approximately one month posttransplant before increased viral shedding begins. PTLD is almost never seen during this interval. In many cases infection continues to be silent whereas in rare individuals there is an overwhelming polyclonal proliferation of infected B lymphocytes. This is the parallel of infectious mononucleosis occurring in patients with a congenital defect in virus handling (X-linked lymphoproliferative disorder). It is possible that transplant patients with this presentation also suffer a defect in virus handling. In other cases excessive iatrogenic immunosuppression may paralyze their ability to respond to the infection. With CsA and FK506 regimens, individual tumors may occur within a matter of months following transplant. The short time of incubation suggests that these are less than fully developed malignancies. It may be that local events conspire to allow outgrowth of limited numbers of B-lymphocyte clones. A cytokine environment favoring B-lymphocyte growth may be one factor and differential inhibition by the immuno-suppressive drugs of calcium-dependent and -independent B-cell stimulation may be another. In addition, there is some evidence that CsA itself may inhibit apoptosis within B cells. Since most patients do not develop PTLDs, an additional signal(s) for B-cell stimulation may be required. Indeed, it is possible that the virus may simply serve to lower the threshold for B-cell activation and/or provide a survival advantage to these cells. The ability of individual cell clones to evade a weakened immune system may set into play a Darwinian type of competition in which the most rapidly proliferating cells with the least number of antigenic targets predominate. In this regard, differences in host HLA types may determine the repertoire of viral antigens which are subject to attack.(ABSTRACT TRUNCATED AT 400 WORDS)
Cytokines are endogenous small peptides that regulate cell growth and proliferation. In allogeneic transplantation, they function as critical immunologic mediators. Allograft rejection is dependent on interactions between antigen-presenting cells, T lymphocytes, accessory molecules, and proinflammatory cytokines (interleukins-1, -2, and -6; interferon-gamma; and tumor necrosis factors). Alternatively, other cytokines (interleukins-4, -5, and -10; transforming growth factor-beta) may suppress allograft rejection. Observation and manipulation of cytokine responses are an essential component of the immunopharmacology and clinical management of transplant recipients. Specific areas of interest include immunologic monitoring, pharmacologic immunosuppression, monoclonal antibody development, induction of tolerance, and the OKT3-related cytokine release syndrome. This review explores the impact of advances in cytokine physiology and biotechnology on clinical transplantation.
Forty-six consecutive adult patients underwent 51 orthotopic liver transplants in a prospective study to evaluate sequential induction with ORTHOCLONE OKT3 (muromonab-CD3), prostaglandin E1, cyclosporine, azathioprine, and methylprednisolone. Infection prophylaxis included preoperative bowel preparation and ganciclovir if cytomegalovirus was diagnosed in either donor or recipient. All rejection episodes were documented by liver biopsy before treatment. Seventy-four percent of patients evaluable beyond 1 year have had no rejection episodes. The retransplant rate was 10%, with a 4% primary nonfunction rate. There was no rejection of grafts that could not be retreated with OKT3. Forty-two percent (5 of 12) of rejection episodes responded to steroid recycling alone. The infection rates for all patients at 1 year were 54% bacterial, 17% fungal, and 22% viral. Three septic deaths were attributed to overimmunosuppression. Two-year patient and graft survival rates were 80% and 72%, respectively. This OKT3 induction protocol results in limited rejection episodes without increasing infections, yielding an acceptably low rate of graft loss.
The goal of any posttransplant immunosuppressive regimen is to prevent allograft rejection while minimizing infectious complications. We hypothesized that sequential induction immunotherapy using the monoclonal antibody ORTHOCLONE OKT3 (muromonab-CD3) would meet these objectives effectively. We have therefore used such a protocol since July 1988 for all pediatric patients undergoing liver transplantation at Children's Hospital Medical Center of Cincinnati. Initial immunotherapy consisted of OKT3, administered preoperatively and then QD, methylprednisolone, and azathioprine. Cyclosporine was begun on POD 3-5, and OKT3 was discontinued when therapeutic cyclosporine levels were achieved for 48 hours. Rejection has not occurred throughout the lifetime of the allograft in 55% of long-term survivors. In the 28 patients who experienced rejection episodes, 71% had a single episode, 21% had two episodes, and 7% had a single episode, 21% had two episodes, and 7% had more than two. Rejection occurring after more than 120 days was invariably associated with noncompliance or subtherapeutic cyclosporine levels. The use of an OKT3-based sequential induction protocol resulted in a decreased incidence of acute rejection. Renal function was preserved, and the incidence of infection was not increased. Long-term outcome analysis of this protocol shows excellent patient survival and the near absence of late or chronic rejection.
Symptomatic cytomegalovirus (CMV) infection is a major cause of morbidity and mortality following orthotopic liver transplantation. Early detection and prompt treatment with appropriate medicine are crucial for successful outcome. As an early detection method, we used the CMV antigenemia test which is based on immunocytochemical detection of CMV immediate early antigens in blood leucocytes. CMV immediate early antigens were detected in blood leucocytes with direct immunoperoxidase technique using a horseradish peroxidase (HRP)-conjugated F(ab')2 fragment of human monoclonal antibody (humab C7), designated HRP-C7. Of the 37 living related liver transplantations we performed on pediatric patients between June 1990 and August 1992, we experienced four cases (10.8%) of symptomatic CMV infection: three CMV hepatitis and one CMV peritonitis. They were all treated successfully with a combination of ganciclovir and immunoglobulins. In ABO-incompatible cases ganciclovir was administered prophylactically. Early detection using this method is though to have led to these successful outcomes. It is concluded that HRP-C7 staining of blood leucocytes is useful for the rapid diagnosis of CMV infection.
