Clinical evaluation of equine antithymocyte globulin in recipients of renal allografts: Analysis of survival, renal function, rejection, histocompatibility, and complications

Passive Monoclonal and Polyclonal Antibody Therapies

Passive antibody therapies have a long history of use. In the 19th century, antibodies from xenographic sources of polyclonal antibodies were used to treat infections (diphtheria). They were used often as protection from infectious agents and toxins. Complications related to their use involved development of immune complexes and severe allergic reactions. As a result, human source plasma for polyclonal antibodies became the preferential source for antibodies. They are used to treat infection, remove toxins, prevent hemolytic disease of the newborn, modify inflammatory reactions, and control autoimmune diseases. Continued improvements in processing decreased the transfusion/infusion transmission of infections. In the late 20th century (∼1986), monoclonal antibodies were developed. The first monoclonal antibodies were of xenographic source and were wrought with problems of immunogenicity. These forms of antibodies did not gain favor until chimerization took pace in the mid-1990s and in 1998 two monoclonal antibodies were approved one to treat respiratory syncytial virus and the other for breast cancers. Further development of humanized and then fully human monoclonal antibodies has led to an evolution of therapies with these agents. Monoclonal antibodies are being researched or approved to treat a multitude of diseases to include oncologic, inflammatory, autoimmune, cardiovascular, respiratory, neurologic, allergic, benign hematologic, infections, orthopedic, coagulopathy, metabolic and to decrease morbidity of disease (diminution of pain), modify disease progression, and potentially anatomic development. In this chapter, we will review the history of use of these passive antibody therapies, their mechanism of action, pharmacologic-therapeutic classification, particular medical indication, adverse reactions, and potential future use of these medications.

Transplant research in nonhuman primates to evaluate clinically relevant immune strategies in organ transplantation

Research in transplant immunology using non-human primate (NHP) species to evaluate immunologic strategies to prevent rejection and prolong allograft survival has yielded results that have translated successfully into human organ transplant patient management. Other therapies have not proceeded to human translation due to failure in NHP testing, arguably sparing humans the futility and risk of such testing. The NHP transplant models are ethically necessary for drug development in this field and provide the closest analogue to human transplant patients available. The refinement of this resource with respect to colony MHC typing, reagent and assay development, and availability to the research community has greatly enhanced knowledge about transplant immunology and drug development.

The role of Thymoglobulin induction in kidney transplantation: an update

The rabbit antithymocyte globulin Thymoglobulin first became available over 25 yr ago and is the most widely used lymphocyte-depleting preparation in solid organ transplantation. Thymoglobulin targets a wide range of T-cell surface antigens as well as natural killer-cell antigens, B-cell antigens, plasma cell antigens, adhesion molecules and chemokine receptors, resulting in profound, long-lasting T-cell depletion. Randomized studies have established the anti-rejection efficacy of Thymoglobulin in kidney transplantation. Experimental and clinical data suggest that Thymoglobulin administration may ameliorate ischemia reperfusion injury, thus reducing the incidence of delayed graft function (DGF). Studies have demonstrated the benefit of using Thymoglobulin to facilitate immunosuppression minimization, both for corticosteroid and calcineurin inhibitor (CNI) withdrawal or avoidance, with potential improvement in cardiovascular and renal outcomes. The optimal cumulative dose for Thymoglobulin induction is 6-7.5 mg/kg, with vigilant short- and long-term monitoring of hematological status. Induction with Thymoglobulin is now indicated in immunologically high-risk patients, in those at increased risk of DGF and to maintain efficacy in low-risk transplant recipients receiving steroid or CNI minimization or avoidance regimens. We suggest that in future trials Thymoglobulin be tested with costimulation signal blockers and other immunosuppressants with the objective of establishing operational tolerance.

B-cell activity of polyclonal antithymocyte globulins

Polyclonal antithymocyte globulins (AThG) are a subset of antilymphocyte antibody preparations derived from the sera of rabbits or horses immunized with unfractionated cells isolated from pediatric human thymi. In vivo, AThG preparations have been used to successfully treat antibody mediated rejection in kidney transplant recipients. In vitro, AThG can induce apoptosis of naïve and memory B cells and terminally differentiated plasma cells. The presence of B-cell reactive antibodies in AThG results from a thymic inoculum containing a significant percentage of CD20(+) B cells and CD138(+) plasma cells. In this paper, the experimental and clinical evidence supporting the B-cell activity of AThG preparations, and their mechanisms of action, are reviewed.

Antithymocyte globulin in cadaver kidney transplantation: a randomized trial based on T-cell monitoring

The influence of horse antihuman thymocyte globulin (ATG) on renal allograft survival was assayed between March 1977 and August 1978. Fifty consecutive patients were randomly assigned to the treatment or the control group. Patients in both groups received azathioprine and prednisolone. ATG was added in the experimental group. The daily dosage was such as to maintain the rosette-forming cell (RFC) level at 10% of baseline values. The number of renal failure episodes (RFE's)was significantly lower in the experimental group during the period (1 month) ATG was given than it was in the control group during that same period of time. Two years after transplantation, kidney survival was 79% in the ATG group and 52% in the control group. The amount of steroids necessary to control RFE's was significantly lower in the ATG group. The dosages of ATG used in the experimental group were relatively small (average daily dose, 3.08 +/- 0.26 mg/kg of body wt), and adverse reactions were mild. Blood tolerance was excellent. T-cell monitoring thus appears to be an effective method in evaluating the daily dosage of ATG.

Diagnosis of impaired renal function after kidney transplantation using renal scintigraphy, renal plasma flow and urinary excretion of hippurate

The use of 131I-orthiodohippurate (OIH) scintigraphy combined with the estimated renal plasma flow (ERPF) and excretion index (EI) has been beneficial in separating impaired renal function due to graft rejection from acute tubular necrosis, ureteral obstruction, urinary extravasation and in some instances renal artery occlusion. The radionuclide data accurately identified acute and chronic rejection, confirmed by the clinical course, increase in BUN and serum creatinine and on occasion renal biopsy. Reversible and irreversible acute tubular necrosis (ATN) were clearly differentiated from acute rejection. When the ERPF and EI were plotted on a graph, multiple sequential radionuclide studies accurately predicted graft survival when chronic rejection existed. The limitation of this technique was the inability to discriminate between renal artery stenosis, ureteral obstruction and inflammatory disease. Scintigraphic studies did not distinguish between renal artery stenosis and chronic rejection. In these circumstances arteriography was the diagnostic procedure of choice. Although ureteral obstruction often can be correctly diagnosed by scintigrams, the ERPF, EI and intravenous pyelogram remained the most accurate diagnostic procedures. Recurrent glomerulonephritis, gram negative septicemia and generalized viral illness (herpes zoster or cytomegalovirus) simulated acute rejection and had to be separated by renal biopsy or the clinical course. The most valuable features of the radionuclide technique included: 1) the noninvasive method, 2) the simplicity, 3) the rapidity and 4) the reproducibility.

Antibody--antigen complex stimulated lysis of non-sensitized sheep red cells by human lymphocytes. I. Requirements for IgG complexes

IgG antibody--antigen complexes stimulated lysis of non-sensitized sheep erythrocytes (SRBC) by normal human peripheral blood lymphocytes (PBL). Heat-aggregated human IgG, rabbit IgG-ovalbumin complexes and rabbit IgG-sensitized ox erythrocytes (ORBC) were effective in the induction of SRBC lysis by PBL. However, IgM-sensitized ORBC and IgM-complement-sensitized ORBC were ineffective. As only SRBC and not ORBC or chicken erythrocytes (CRBC) were lysed under identical experimental conditions, it is conceivable that the SRBC receptor present on the T cell is involved. Furthermore, 45% inhibition of lysis was obtained by pretreating the effector cells with anti-human thymocyte globulin (ATG) and complete inhibition was obtained by adding SRBC stroma to the reaction mixture. The requirement for the inclusion of IgG complexes and the absence of specific anti-target cell antibody distinguish this reaction from natural cell-mediated cytotoxicity and antibody-dependent cell-mediated cytotoxicity (ADCC). Immune killer T cells would not appear to be responsible as eight different donors were used and none of these were cytotoxic to SRBC in the absence of IgG complexes. The induction of this cytotoxic reaction appears to require the recognition and interaction by the effector cells of two separate molecular entities, i.e. the SRBC membrane by the T cell and the IgG Fc region by an IgG-Fc receptor-bearing cell.

The effect of serum ALG concentrations on results following renal transplantation

Seventy-three recipients of renal allografts from cadaver donors, and 121 recipients of kidneys from living related donors were studied to determine whether there were any differences in posttransplant results between patients that had a high average serum concentration of ALG (>/=800 microg/ml) during the two weeks of ALG therapy and patients that had low serum levels (</=799 microg/ml). Cadaver kidney recipients who had high serum ALG levels (average 1126 microg/ml) had significantly fewer rejection episodes three months posttransplant and less kidney loss three and six months posttransplant when compared to patients with low serum ALG concentrations (average 629 microg/ml). The tendencies after three and six months favored the group with high serum ALG levels, but the differences were not statistically significant. There were also significantly fewer rejection episodes and less kidney loss at three months in the group with serum ALG levels >/=800 microg/ml when high risk patients with diabetes mellitus were excluded. There were significantly also fewer rejection episodes at three months in recipients of living related kidney grafts that had serum ALG levels >/=800 microg/ml. When high risk diabetics or patients older than 40 were excluded from the related recipients, the number of rejection episodes was still significantly less in patients with high serum ALG levels. There was significantly less kidney loss 24 and more months posttransplant in recipients of kidneys from living related donors whether or not high risk patients were excluded. These results support previous reports from the University of Minnesota indicating ALG is a safe and effective immunosuppressive agent in renal allograft recipients.

100 sibling kidney transplants followed 2 to 7 1/2 years: a multifactorial analysis

From January 1, 1968 to May 31, 1973, 100 patients received first kidney transplants from sibling donors. All recipients have been followed for at least two years and several as long as 7.5 years. One hundred per cent follow-up information is available. The absolute two-year patient survival is 85% and the absolute two-year kidney function survival is 76%. Patients with diabetes (especially males) have less success following transplantation than do patients without diabetes. When diabetic patients are excluded, older patients appear to do slightly less well than younger patients. Patients with phenotypically identical HL-A matches with the donor do better than patients without such matches. In the nondiabetic technically perfect transplant recepient, better than 90% long-term transplant function can be expectedwith no kidney losses after the first few months. In contrast, the less well-matched transplant demonstrated both an increased early rejection rate and a high rate of loss after the third to fifth year. Increasing doses of anti-lymphoblast globulin (ALG) had beneficial results in HL-A mismatched sibling transplants, but were slightly detrimental in phenotypically identical HL-A donor-recipient pairs because of an increased rate of infection. The results are compared with the results of transplants from other related donors and from cadavers performed during the same period.

115 patients with first cadaver kidney transplants followed two to seven and a half years. A multifactorial analysis

One hundred fifteen consecutive patients received first transplants from cadaver donors at the University of Minnesota between January 1, 1968, and May 31, 1973. All patients have been followed for at least two years. The two-year survival rate is 70 per cent and the two-year transplant function rate is 58 per cent. Considerable improvement in both patient survival and transplant function has been noted since 1971. The success of transplantation appears to depend to a large degree on the age of the transplant recipient, the number of HLA antigens matched between donor and recipient, and the dose of antilymphoblast globulin (ALG) administered to the recipient during the first two weeks after transplantation. Each of these factors appears to be important even when the other factors are controlled, and when patients with diabetes, suffering technical failure or hyperacute rejection, are excluded. The results utilizing well-matched cadaver kidneys plus large doses of ALG appear to be equivalent to those obtained with the use of mismatched kidneys from relatives, but further analysis will be required to draw a definite conclusion. Patients receiving poorly-matched cadaver kidneys do far less well than patients receiving mismatched related grafts, however, even when ALG is utilized.

Retrospective analysis of 100 consecutive patients undergoing related living donor renal transplantation

One hundred consecutive patients receiving related donor kidneys were analyzed in regards to graft and patient survival, morbidity, mortality, histocompatibility and rehabilitation. The average followup was 3 years and 2 months with a minimum post transplant evaluation of one year. Donor morbidity was minimal and the mortality nil. Recipient mortality was 17%, all of which occurred after the first two post transplant months. The most serious life threatening complications after transplantation were due to infection. The greatest morbidity was secondary to aseptic necrosis. The overall graft survival at one year was 94%, 2 years--87%, 3 years--81% and 4 and 5 years--72%. Separation of patients according to tissue typing revealed 95% of recipients with A and B matched kidneys to be alive 5 years later compared to 55% of patients receiving C and D matched kidneys. Rehabilitation was good to excellent in 76% of the living patients and poor in only 4%. These results suggest related donor renal transplantation to be the treatment of choice for patients with chronic renal failure excluding only those individuals who are exceptionally high risks in terms of morbidity and mortality.

Kidney transplantation in patients with end stage congenital renal disease. Report of eighteen cases and review of the Organ Transplant Registry

Eighteen patients with end stage congenital renal disease requiring kidney transplantation constituted 12 per cent of the transplantation recipients at this institution over the past six years. The post-transplantation course in this group was remarkably satisfactory, with a 94 per cent graft survival at three years. In addition, we analyzed survival data from over 9,900 patients in the Organ Transplant Registry and demonstrated that transplant recipients with end stage congenital renal disease have equal or better five year patient survival compared with those with acquired end stage renal disease. Only those patients with adult polycystic disease had a less satisfactory prognosis, probably because of age-related factors. In contrast, there were few statistical correlations between renal allograft survival, age, and original disease.