Studies on the rosette inhibition assay. Improvement of the method and correlation with monkey skin graft prolongation.

The rosette inhibition assay for immunosuppressive activity of antilymphocyte globulin or plasma has been studied in an effort to improve its reliability. Important changes include the elimination of calcium and magnesium ions from salt solutions used in the assay, the use of deoxyribonuclease to prevent lymphocyte clumping, and pretreatment of plasma samples (heating at 63 C for 10 min followed by acrinol precipitation) to prevent nonspecific inhibition of rosette formation. The use of a graded dose response potency assay against a house standard is discussed. A significant correlation was established between the in vitro activity of several series of antilymphocyte globulin or antithymocyte globulin preparations and their ability to prolong skin graft survival in primates. The best correlation was achieved using a potency estimate relative to a house standard, rather than the conventional titer estimate.

Manufacture of antithymocyte globulin (ATGAM) for clinical trials.

Methods are described for preparing large amounts of horse anti-human thymocyte globulin (ATG, ATGAM; The Upjohn Company) for clinical use. These methods have been used since 1968 to provide material for clinical trials. Characteristics of 40 lots of ATG are summarized.

Efficacy of induction therapy in cadaveric renal transplantation comparing rabbit antithymocyte serum and Minnesota antilymphoblast globulin.

From August 1986 to July 1989, 98 patients receiving primary cadaveric kidney transplants received either RATS (n = 50) or MALG (n = 48) during the induction phase of a quadruple immunosuppressive protocol. Patient groups were well matched. The duration of RATS and MALG treatment and the time of CyA induction were equivalent. Serum creatinine and rejection episodes up to 1 year were not statistically different. Hematologic side effects resulted in dose reduction of MALG in 42% of patients without adverse rejection results. In the RATS group, no dosage reductions were required. One-year patient survivals (96% to 100%), and 1-year graft survival (82% to 85%) were not significantly different in the 2 groups. Infectious complications were 30% higher in the MALG group and a significant factor in 2 deaths. Monitoring of lymphocyte subsets revealed insignificant differences in the percent of decrease of each cell population between MALG and RATS groups during induction.

The clinical problems of dosage and the route of administration of antilymphocyte globulin.

The production and quality control of ALG are outlined. The advantages and disadvantages of the various routes of administration of ALG are discussed. We tend to use a short duration high dose course of ALG in renal transplantation, myasthenia gravis and polyarteritis nodosa.

[Potency determination of horse anti-human-lymphocyte serum (ALS) by means of the lymphocyte resistance test, a modification of Schroder's leukocyte resistance test]. / Zur Wertigkeitsbestimmung von Pferde-Antihumanlymphozytenseren (ALS) mit dem Lymphozytenresistenztest, einer Modifikation des Schröderschen Leukozytenresistenztests

The leukocyte resistance test of Schröder was used for the purpose of modifying the in vitro determination of cytotoxic potency of ALS during the course of immunization. In contrast to the original method, where the test was carried out with whole blood, the incubation was made with pure lymphocyte cell suspensions. The results obtained show that the extensive procedure of examination enables the cytotoxic effectiveness of antilymphocytic antibodies to be evaluated.

Development, production and quality control of clinically applied antilymphocyte globulin.

Various antigens have been assessed for the ability to produce anti-human lymphocyte globulin(ALG). In our hands the most satisfactory antigen has proved to be cultured lymphoblasts. These are used to produce Behringwerke ALG(Pressimmune). A brief outline of problems in the large scale production of ALG and how these are overcome is given. The quality control checks for activity and safety are discussed.

Biological and immunological characterization of ATG and ALG.

Antithymocyte globulin (ATG) and antilymphocyte globulin (ALG) are effective therapies in aplastic anemia; their mechanism of action is undefined. We assayed multiple properties of ATG and ALG to address the biological and immunological bases for differences between ATG and ALG and lot variation. In addition, we studied a lot reported to be inactive in an American clinical trial; however in retrospect, this lot appeared to be active in patients treated in Europe. Immunoprecipitation of thymocyte and lymphocyte membrane proteins with ATG and ALG showed between 14 and 18 major bands on SDS-PAGE, but the patterns for ATG and ALG were not identical. The ability of ATG and ALG to block binding of labeled monoclonal antibodies was assessed using flow cytometry and a radioimmunoassay. In general, there was more lot variation among ALGs than ATGs; however, all ALG lots were more potent blockers of binding of anti-HLA-DR and anti-Leu 1 antibodies than was ATG. Both ALG and ATG effectively blocked binding of anti-Leu 2a, anti-Leu 3a, anti-Leu 4, anti-Leu 5b, and anti-IL 2 receptor abs; neither blocked binding of anti-Leu 7. All preparations were capable of inducing T-cell blastogenesis, although there was considerable lot variation. All lots lysed 60% to 75% T cells in a rabbit complement-mediated cytotoxicity assay, with most having a plateau of activity at 5 to 10 ug/mL. Two lots of ALG, including the lot reported to be clinically inactive, showed less toxicity at suboptimal concentrations and did not plateau even at 80 ug/mL. In total, these results indicate important differences between ATG and ALG in general, more lot variation among ALGs than ATGs and only differences in cytotoxicity between an "inactive" lot of ALG and most, but not all, other active ATG and ALG preparations.

Effect of antilyphocyte-globulin potency on survival of cadaver renal transplants. Prospective randomised double-blind trial.

71 recipients of cadaver primary and secondary renal transplants were investigated in a prospective randomised double-blind study. Patients were given one of two rabbit antilymphocyte globulin (A.L.G.) preparations made by similar techniques but differing in potency as measured by skin-graft prolongation in rhesus monkeys. Patient selection and management were otherwise similar. A statistically significant difference (P less than 0-05) in graft survival (78% vs. 42%) developed between the two groups at a mean follow-up of 18-4 months and patient entry into the study was terminated. After a 3-5 year interval from the start of the trial the double-blind code was broken. It was found that the high-potency-A.L.G. group had better graft survival and fewer rejection episodes (P less than 0-05) than the moderate-potency group. The results suggest that preclinical testing of A.L.G. by the primate skin graft test can be a valid indicator of the potential efficacy of an A.L.G. preparation in renal-transplant recipients. It is suggested that quality-control standards may improve the clinical results of A.L.G. therapy.