Advances in the treatment of lupus nephritis

Systemic lupus erythematosus (SLE) is an autoimmune disease that leads to the formation and deposition of immune complexes throughout the body, which are pathogenic for the disease. Different forms of glomerulonephritis can occur in patients with SLE and can contribute significantly to the associated morbidity and, ultimately, mortality from the disease. Over the past two decades, there have been significant strides in our understanding of the disease and in treatments that attempt to control the formation and deposition of anti-DNA auto-antibodies and immune complexes, as well as the subsequent inflammatory cascade mediated through various cellular and humoral pathways leading to progressive renal damage and end-stage renal disease. In this chapter, we review the current understanding of the pathogenesis and treatment of lupus nephritis in its various stages and discuss the experimental and human data regarding some of the potential newer forms of therapy. We discuss data regarding the use of steroids, azathioprine, cyclophosphamide, cyclosporine A, mycophenolate mofetil, gammaglobulin, plasmapheresis, LJP 394, flaxseed oil, bindarit, anti-CD40 ligand, and CTLA4Ig.

Isolation, identification and immunosuppressive activity of SDZ-IMM-125 metabolites from human liver microsomes

SDZ-IMM-125 N-methyl leucine 9 hydroxylated in the gamma position is a metabolite which was extracted from incubated human liver microsomes and subsequently separated by normal and reverse-phase HPLC. This metabolite was identified by fast atom bombardment mass spectrometry, electrospray-ms/ms mass spectrometry and nuclear magnetic resonance spectroscopy. The in vitro 50% inhibitory concentration, tested against bidirectional mixed lymphocyte reaction was 80 microg/l indicating that this metabolite does not retain in vitro immunosuppressive activity most probably due to the structural modification of SDZ-IMM-125 in the recognized binding region to cyclophilin A reducing its binding affinity relative to the parent drug.

Cross-reactivities of cyclosporin G (NVa2 cyclosporin) and metabolites in cyclosporin A immunoassays

Immunoassays of cyclosporin A (CsA) have been routinely used to measure CsG. We investigated the cross-reactivities of CsG and its metabolites, as well as the proportion CsG constitutes in relation to total drug measured, for six CsG metabolites (GM1, GM9, GM4N, GM1c, GM1c9, GM19) in the following CsA assays: Sandimmune selective RIA (SS), Sandimmune nonselective RIA (NS), Cyclotrac SP-RIA (CT), fluorescence polarization immunoassay (FPIA), and enzyme immunoassay (EMIT). The cross-reactivity of CsG in these assays was as follows: SS, FPIA, CT, approximately 100%; NS, approximately 40%; EMIT, < 2%. The cross-reactivities of CsG metabolites were investigated in all assays except EMIT and varied among metabolites and assays. The most significant variance was found with the NS assay, where most of the metabolites exhibited cross-reactivities of > 40%. In contrast, in the SS, FPIA, and CT assays, cross-reactivities of < 5% were observed for most of the metabolites. The ranking of cross-reactivities of CsG metabolites in the assays is SS = CT < FPIA < NS. The degree of cross-reactivity did not change significantly when the SS, CT, and FPIA assays were calibrated with CsG instead of CsA--whether parent CsG was present or not. The data suggest that the SS, CT, and FPIA methods would be suitable for the routine monitoring of CsG.

New cyclosporin A analogue: synthesis and immunosuppressive activity

A synthetic analogue of cyclosporine A, in which an unusual amino acid (4R)-N-methyl-4-butenyl-4-methyl-L-threonine (MeBmt) is replaced with L-threonine (Thr), was synthesized by the solid phase method. Its activity in the humoral response to sheep red blood cells in vitro and in vivo in mice was practically the same as that of cyclosporine A used as a standard, whereas the analogue studied exerted a significantly stronger effect in the delayed type hypersensitivity to sheep red blood cells in mice.

Comparison of the properties of the CsA analogs monoacetyl CyC (o-acetyl-threonine2 cyclosporin) and methyl-alanyl CsA (N-methyl-L-alanyl6 cyclosporin); monoacetyl cyclosporin is immunosuppressive without binding to cyclophilin

Cyclosporin (CsA) is an immunosuppressant which binds to cyclophilin (Cyp). The relationship between Cyp binding and immunosuppression has been questioned since one of the analogs of CsA, N-methyl-L-alanyl6 cyclosporin (methyl-alanyl CsA) binds to Cyp but is not immunosuppressive. We compared the immunosuppressive properties of CsA, methyl-alanyl CsA and o-acetyl-threonine2 cyclosporin (monoacetyl CyC), since monoacetyl CyC does not bind to Cyp when tested in cell-free assays and its immunosuppressive properties had not been tested. Cyp is a peptidyl-prolyl isomerase which is abundant in all human tissues, yet the activities of CsA are mostly confined to inhibition of T cell and thymocyte activation, and to neuro- and nephro-toxicity and are independent of inhibition of the isomerase. Activation of thymocytes and of T cells is regulated by the binding of a nuclear factor(s) (NFs) to the NF-AT region (-285 to -255) of the IL-2 promoter. We studied inhibition of binding to the NF-AT region of NFs derived from primary cultures of thymocytes treated with CsA or its analogs. In addition, we compared the effect of CsA and its analogs on the expression of the IL-2 gene in a stably transfected Jurkat-cell line (Fgl 5) which contains three copies of NF-AT and the reporter enzyme beta-galactosidase; and on inhibition of proliferation induced by concanavalin A (Con A) or IL-2. We found that monoacetyl CyC which does not bind to Cyp is immunosuppressive by our criteria when tested in cultured cells due to either a different mechanism of action or to metabolic activation.

The isolation, structural characterization, and immunosuppressive activity of cyclosporin G (NVa2-cyclosporine) metabolites

Seven cyclosporin G metabolites were isolated by high-performance liquid chromatography from the urine of normal subjects receiving the drug. The structure and purity of the metabolites were assessed by fast atom bombardment/mass spectroscopy, by proton nuclear magnetic resonance (NMR), and by 13C-NMR. The structural modifications of the cyclosporin G metabolites consisted primarily of hydroxylation and demethylation, as is the case for cyclosporin A metabolites. The immunosuppressive activities of the metabolites were tested in three separate in vitro systems: a primary and secondary mixed lymphocyte system, as well as a mitogen stimulated system. In general, the metabolites have immunosuppressive activity of less than 10% of cyclosporin G. The significance of these findings in relation to the therapeutic monitoring of cyclosporin G is discussed.

[Non-immunologic effects of cyclosporins]

Cyclosporins are a group of molecules produced by fungi. The main cyclosporin, cyclosporin A, is widely known for its immunologic properties which have made it the leading drug for prophylactic therapy of transplant rejection. However, cyclosporin A (as well as several of its analogs with or without immunosuppressive properties) has a broader and more varied spectrum of biologic effects both in vivo and in vitro; renal, pancreatic, endothelial, muscle and nerve cells, hepatocytes, keratinocytes, and some microorganisms (plasmodium, schistosoma) are target cells whose metabolism or growth is affected by cyclosporins. Some of these activities are responsible for adverse effects but others may warrant the use of selected cyclosporins in clinical situations other than organ transplants.

Isolation of cross-reacting compounds to Incstar Cyclo-Trac SP RIA in blood samples obtained from cardiac allograft patients on cyclosporine therapy

To examine the specificity of the Incstar Cyclo-Trac SP RIA kit, individual blood samples from 28 cardiac allograft patients on cyclosporine A (CsA) therapy were extracted and chromatographed by HPLC. Initially, eluates from a pool of the above samples were collected at regular intervals and measured by RIA to locate possible cross-reacting compounds. Unknown cross-reacting materials were detected in a fraction (UNK) that was collected before elution of CsA. For each patient's sample, fraction UNK and the fraction containing CsA were then collected and measured by RIA. In 9 of 28 samples, cross-reactivity was detected in fraction UNK; range 11 to 36%, mean 22 +/- 7.5%. Cross-reactivity was not apparent in fraction UNK of CsA-free blood samples from normal volunteers.

Suppression of immunological response against a novel gene product delivered by implants of genetically modified fibroblasts

We have recently demonstrated the feasibility of genetically modifying autologous primary rat fibroblasts to deliver in vivo a foreign gene product, human growth hormone. However, in this model for gene replacement therapy, all recipient animals developed extremely high titres of antibodies against human growth hormone within two weeks of grafting. We now report on two approaches to suppress this immune-response. First, rats implanted with human growth hormone-secreting rat fibroblasts were treated with an immunosuppressant, cyclosporine A, at 20 mg/kg body weight per day. The production of anti-human growth hormone antibodies in the treated animals was completely blocked during the 12-week course of treatment. Secondly, by using immunologically immature neonatal rats as recipients, the rapid antibody response to the human growth hormone was also avoided. However, after a delay of one month, these rats also developed an extremely high titre of antibodies against the human growth hormone. In comparison, rats in the adolescent, mature and aged groups developed and maintained high titres of antibodies soon after implantation. Therefore, antigenic response against novel gene products can be suppressed either totally by cyclosporine A or temporarily in neonatal animals. The combination of early implantation and subsequent immuno-suppression should be considered in somatic gene therapy for those patients who are negative for cross-reacting-material and may be expected to mount an antigenic response to the replacement gene product.

Analysis of the structural diversity of monoclonal antibodies to cyclosporine

The immunosuppressive cyclic undecapeptide cyclosporine (Cs) represents a useful model for studying the molecular basis of antibody-antigen interactions. The three-dimensional structure of the Cs molecule is known and a large panel of monoclonal antibodies (mAbs) to Cs has been well characterized by cross-reactivity studies with numerous Cs analogs. In the present study, the sequences of the variable regions of seven mAbs to Cs were determined and a striking relationship was found between the expressed variable region genes and the Cs recognition pattern. An analysis of the length and hydrophobic content of the hypervariable regions and sequence similarities suggested that the heavy chain plays a major role in Cs recognition. Different fine specificities were observed for mAbs exhibiting identical light chains, while two antibodies differed by only a single amino acid located in the heavy chain. The presence of a duplication of 12 nucleotides within the heavy chain third hypervariable region of two antibodies suggests the existence of an additional mechanism for creating antibody diversity.

Chemiluminescence immunoassay of cyclosporine in whole blood

We describe a chemiluminescent immunoassay (CLI) for measuring cyclosporine in whole blood. Its sensitivity and accuracy are comparable with those of an RIA method that makes use of the same specific monoclonal antibody. The comparison with the RIA method was excellent: y(RIA) = x(CLI) + 11.24 (r = 0.99). In our procedure the samples are incubated with cyclosporin C-hemisuccinate-aminobutyl-N-ethylisoluminol, antibody, and paramagnetic particles coated with second antibody. After magnetic separation and washing, the samples are incubated with 200 microL of NaOH (2 mol/L) at 60 degrees C for 30 min. The chemiluminescence generated by automated serial injections of solutions of microperoxidase and dilute (2 mL/L) H2O2 is measured for 5 s. The data are processed by using a spline fit of log B/Bo log conversion. This method is easy to perform and avoids the hazards and costs associated with isotopic waste disposal. The label is stable for at least three years.

A validation study of selected methods routinely used for measurement of cyclosporine

We compare four methods for measuring cyclosporine (CyA) in plasma and whole blood of transplant patients: HPLC, RIA with a polyclonal antibody, RIA with a monoclonal antibody, and fluorescence polarization immunoassay (FPIA). The monoclonal RIA procedure correlated acceptably with HPLC, with slope = 1.21, r = 0.97, and Sy,x = +/- 40.1. However, the FPIA, done in three separate instruments, correlated relatively poorly with HPLC, giving slopes of 1.67, 1.51, and 2.32; correlation coefficients of 0.72, 0.43, and 0.83; and Sy,x = +/- 205.4, +/- 334.5, and +/- 222.4. The polyclonal RIA correlated reasonably well with HPLC, with a slope = 1.15, r = 0.90, and Sy,x = +/- 72.6. Values for individual patients with increases both in gamma-glutamyltransferase and creatinine showed very poor correlation between FPIA and HPLC, which suggests that metabolite cross-reactivity with FPIA is significant and unpredictable in patients with liver dysfunction coexisting with renal dysfunction. Evidently, the monoclonal RIA can be substituted for HPLC, if the therapeutic range is adjusted for the 21% higher results obtained by RIA.

Monoclonal antibodies to cyclosporin are representative of the major antibody populations present in antisera of immunized mice

Two series of mouse antisera raised against cyclosporin (Cs)-carrier conjugates exposing opposite sides of the Cs molecule and more than sixty monoclonal antibodies (mAbs) derived from the same animals were compared in terms of isotype and fine specificity for Cs. The predominant isotypes of the mAbs reflected the in situ distribution of the circulating anti Cs antibodies. The fine specificity of the antibodies was studied by determining their cross-reactivity for a series of Cs-derivatives and Cs-metabolites in competitive ELISA. The antisera raised by different immunizations showed very different cross-reactivity patterns for the Cs-derivatives. However, the in situ anti Cs antibody populations and the majority of mAbs derived from the corresponding animals showed a striking similarity in fine specificity for restricted clusters of residues on the Cs molecule. These results indicate that the mAbs produced against Cs are representative of the major antibody population present in the sera of the mice used for the fusion. By determining the characteristics of antibodies found in the serum of immunized mice it may thus be possible to select animals that are likely to give rise to mAbs of a certain isotype and specificity.

Immunosuppressive activity of cyclosporine metabolites compared and characterized by mass spectroscopy and nuclear magnetic resonance

Eight cyclosporine (CsA) metabolites were isolated from the urine of renal-transplant patients by high-pressure liquid chromatography. Structure and purity of the metabolites were assessed by fast atomic bombardment/mass spectroscopy, by proton nuclear magnetic resonance (NMR), and, when the quantity of metabolites permitted, by 13C-NMR. The immunosuppressive activities (I) of the metabolites were tested in three separate in vitro systems: primary and secondary mixed lymphocyte reactions as well as by a mitogen-stimulated system. The I, as measured by comparing the concentration of each metabolite required for 50% inhibition of incorporation of [3H] thymidine, varied among the assay systems, as did the ranking of I among the test systems. In general, the I of most metabolites in all assay systems were less than 10% of that for CsA. Metabolites with single modifications exhibited the greatest I; e.g., that of M-17 was congruent to 16% of that of CsA (potency ratio 0.16) in a secondary mixed lymphocyte reaction. The significance of these findings in relation to therapeutic monitoring of CsA is discussed.

The mechanisms of action of cyclosporine

CS most probably manifests its immunosuppressive effects by inhibiting the synthesis of IL-2 and other lymphokine mRNAs during the process of T-cell activation. The detailed molecular events involved in CS's inhibition of mRNA synthesis are not known, but it is likely that the drug prevents transduction of the mitogenic signal from the cell surface to the nucleus at a point subsequent to the rise in intracellular calcium generated by the mitogenic signal. CS immunosuppression also appears to be related to the binding of an intracellular receptor protein, cyclophilin, which is a major cytosolic constituent of all cells and has peptidyl-prolyl isomerase activity. The involvement of this protein in T-cell activation, if any, is not yet known. Studies on the biochemical basis of CS-induced nephrotoxicity are still in their infancy and the relation of toxicity to immunosuppression is not understood. It is evident that the mode of action of CS provides an intriguing puzzle and a challenge in both its immunosuppressive and nephrotoxic aspects. The elucidation of the biochemistry of CS will surely not only improve the use of this important drug but will also increase our understanding of T-lymphocyte activation and the mechanism underlying the control of gene expression.

Three commercial polyclonal immunoassays for cyclosporine in whole blood compared: 2. Cross-reactivity of the antisera with cyclosporine metabolites

We demonstrate the diverse selectivity of three commercial polyclonal "cyclosporine" immunoassays for cyclosporin (CsA) metabolites by comparing analytical responses of nine metabolites added to drug-free whole-blood specimens (range 0 to 2000 micrograms/L) and assayed by the Abbott TDx fluorescence polarization immunoassay (FPIA), the Incstar Cyclo-Trac radioimmunoassay (RIA), and the Sandoz RIA. Cross-reactivity--defined as the relative response (slope of regression line) of metabolite/parent CsA over the assay's linear range of concentrations--differed for each metabolite among the three assays. Overall, Abbott's antiserum exhibited the greatest affinity for the metabolites, the Sandoz antiserum the least. Ranges of cross-reactivity for the metabolites over all three assays were M1 (14-44%), M8 (9-20%), M13 (13-26%), M17 (50-116%), M18 (17-79%), M21 (4-54%), M25 (less than 1-52%), M26 (less than 1-29%), and M203-218 (7-51%). The specificities of the Abbott, Incstar, and Sandoz polyclonal assays thus differ significantly, and this brings into question the practical utility of comparing data generated for patients' specimens by different procedures.

Canine models of bone marrow transplantation

Progress in experimental bone marrow transplantation in dogs has provided for the direct transfer of research data to the clinical setting and the therapeutic application of marrow grafting to a variety of human diseases. Animal models of total body irradiation, engraftment and graft-versus-host disease are still needed to solve the existing clinical problems of marrow transplantation. Therefore, work in various canine model systems continues to be of interest. Pet dogs with spontaneously occurring lymphomas are used to study the clinical parameters necessary for applying the technique of transplanting their own marrow (autologous), in conjunction with high dose radiation and/or chemotherapy, to human patients with cancer. A major consideration in the successful transplantation of donor bone marrow (allogeneic) is overcoming histocompatibility barriers to assure engraftment and the prevention of graft-versus-host disease, a major limiting aspect of clinical marrow transplantation. Chemicals, radiation, radiotherapeutic techniques, antisera and monoclonal antibodies have been and continue to be developed in laboratory bred dogs. These approaches suppress the immune system either nonspecifically by ablation of immune reactive tissue, or specifically by affecting certain types of immune reactive cells. Parameters such as clinical effectiveness (engraftment or prevention of graft-versus-host disease), immune reconstitution and undesirable side affects in long-term survivors are all used to determine whether new technology can be transferred from preclinical canine studies to human bone marrow transplantation protocols.

An explanation of the noncorrespondence between assessment methods of cyclosporin

Various methods of determining cyclosporin (CyA) levels in patients after kidney transplantation were compared. These included polyclonal antibody (pcAb-), specific and nonspecific monoclonal antibody (S- and NmcAb-) radioimmunoassays (RIA), and high performance liquid chromatography (HPLC). The results obtained by the various methods when compared showed some correlation but did not correspond. A probable explanation for part of this noncorrespondence is the presence of monoclonally crossreactive metabolites (CyA-M). Another reason was that the concentration of CyA in the standards supplied with the RIA kits was found to be higher than stated.

Immune hemolysis after an ABO mismatched renal transplant

We describe a case of immune hemolysis due to anti-B occurring in a blood group B patient 16 days after a cadaveric renal transplantation from a blood group O donor. Transfusional support was initially required and the direct antiglobulin test (DAT) remained positive for 80 days. Cyclosporin A (CSA), which was used for rejection prophylaxis in this case, has unique immunosuppressive capabilities which protects transplanted organs from rejection, but which might permit this type of 'graft versus host' reaction.

Cyclosporine kinetics in renal transplant patients as assessed by high-performance liquid chromatography and radioimmunoassay using monoclonal and polyclonal antibodies

The area under the blood concentration vs. time curves of cyclosporine (24 hr) were determined nonspecifically by the polyclonal RIA, specifically by a monoclonal RIA and by HPLC after an oral and an i.v. dose of CsA in 10 renal transplant patients. The mean blood concentrations determined by monoclonal RIA were 10-20% higher than those measured by HPLC, whereas the concentrations assessed by polyclonal RIA were greater than 100% higher than those determined by HPLC. As a corollary, the pharmacokinetic parameters (clearance, volume of distribution, and systemic availability) differed when the results from the 3 methods were compared. The RIA/HPLC concentration ratio of CsA was higher after oral than after i.v. dosing when RIA measurements were performed by the polyclonal but not by the monoclonal RIA. These ratios changed continuously during the first 12 hr after the administration when the polyclonal but not when the monoclonal RIA was used. In conclusion, blood concentrations assessed by the 3 methods are not identical, and when compared with the polyclonal RIA the monoclonal RIA exhibits 3 advantages: (1) much less crossreactivity with metabolites; (2) a constant RIA/HPLC concentration ratio after the third hr after administration of CsA; and (3) a RIA/HPLC concentration ratio that is independent of the route of administration.

Antibodies to cyclosporine A (CsA) by a novel route and their use to monitor cyclosporine levels by radioimmunoassay (RIA)

Anti-cyclosporine antibodies were generated in rabbits, using an antigen derived from CsA. CsA was linked to carrier proteins by means of a photoactive cross-linking reagent, 4-benzoylbenzoic acid (BBa), an alpha, beta-unsaturated ketone. In the presence of CsA, photolysis of BBa results in hydrogen abstraction and random insertion into the cyclosporine molecule, generating a population of CsA with carboxyl groups at various positions. Immunization with CsA-BBa-bovine serum albumin gave rise to high affinity antibodies to CsA, with Kd = 9.8 +/- 2.8 x 10(-11) M, as determined by Scatchard analysis. Specificity was determined by competition experiments in a radioimmunoassay (RIA), using a panel of six cyclosporine derivatives, substituted at different positions. The derivatives could be arranged into three groups according to their affinities. One derivative with the lowest affinity had a bulky O-t-butyl-D-serine in place of D-alanine in position 8. Serum CsA levels in 25 transplant patients were measured by RIA, and compared to levels determined with a commercially available polyclonal antibody, which is routinely used clinically. The rabbit antiserum gave values that correlated well with the results using the commercial antibody.

Cyclosporine blood levels--an evaluation of radioimmunoassay with selective monoclonal or polyclonal antibodies and high-performance liquid chromatography in liver transplant recipients

Cyclosporine blood levels were measured in 225 blood samples taken 14 days to 3 years after transplantation from 8 adult and 7 pediatric liver graft recipients. Results by high-performance liquid chromatography, radioimmunoassay with a polyclonal antibody (PARIA) or with a selective monoclonal antibody (MARIA) were compared in the context of major clinical events and alterations in serum bilirubin, aspartate aminotransferase, alkaline phosphatase, gamma-glutamyl transpeptidase, urea, and creatinine. Cyclosporine blood levels by MARIA were significantly higher than HPLC values, but only by mean values of 11 micrograms/L in adult and 20 micrograms/L in pediatric patients. These differences were unaffected by alterations in liver or renal function and seem unlikely to affect clinical management. Minimum PARIA:HPLC ratios of 2-4 were noted in patients with good graft function, with higher ratios (up to 18) associated with hepatic dysfunction. Multiple regression analysis demonstrated that elevations in serum bilirubin and alkaline phosphatase significantly contributed toward the correlation with raised PARIA:HPLC ratios in adults and that gamma-glutamyl transpeptidase and aspartate aminotransferase were additionally important in children. There was no significant contribution from either serum urea or creatinine levels to raised PARIA:HPLC ratios, but in children a positive correlation existed between these indicators of renal function and trough cyclosporine concentrations determined by selective methods (HPLC and MARIA).

Isoprinosine potentiation of human peripheral blood mononuclear cell response to mitogens: kinetics and effect on expression of the IL-2 receptor and the activity of interleukin 2

Isoprinosine, a synthetic purine derivative, enhanced the proliferative response of peripheral blood mononuclear cells to the lectin phytohaemagglutinin, and to the monoclonal antibody OKT3. The drug did not potentiate the activation of cells following oxidation by sodium periodate. Isoprinosine had no effect on the expression of receptors for interleukin-2. Increased interleukin-2 activity was detected in three out of nine supernatants from PHA activated mononuclear cells which were cultured in the presence of isoprinosine. Kinetic experiments involving addition or removal of the drug at various time intervals indicated that potentiation of the proliferative response required the presence of the drug at both early and late stages of cell activation. Inhibition of mononuclear cell activation by cyclosporine A was not affected by isoprinosine. These results suggest that enhancement of mononuclear cell proliferation by isoprinosine involves events in both early and late stages of the activation cycle.

Induction and rapid screening of monoclonal antibodies against cyclosporin A

Cyclosporin C-hemisuccinate was coupled to thyroglobulin by the mixed anhydride method. Cyclosporin C was used instead of cyclosporin A (CsA) because of lack of functional groups of CsA. The resulting protein-cyclosporin C conjugate allowed us to induce high antibody titers also against cyclosporin A in rabbit and mice. Polyclonal and monoclonal antibodies were prepared following standard procedure. Since no standard methods for screening and quantification of anti-CsA-antibodies were available, two methods were adapted: (a) liquid phase radio assay (RA) and (b) solid phase enzyme-linked immunoassay (ELI-SA). For the former procedure inactivated charcoal was applied to separate the antibody-bound and the unbound CsA. CsA-coated PVC microtiter plates were used for the latter.

Monoclonal antibodies for radioimmunoassay of cyclosporine: a multicenter comparison of their performance with the Sandoz polyclonal radioimmunoassay kit

The performance of a radioimmunoassay kit containing monoclonal specific and nonspecific antibodies to cyclosporine (Sandimmun-Kit; Sandoz Ltd., Basle, Switzerland) was compared with that of the original Sandoz polyclonal radioimmunoassay kit (Ciclosporin RIA-Kit). A total of 1320 blood and plasma samples from patients receiving cyclosporine after kidney, heart, liver, and bone-marrow transplantation were analyzed at six centers. For blood samples the median result on using the specific assay was about 50% of the polyclonal assay result after kidney and bone-marrow transplantation, about 33% after heart and liver transplantation; comparable figures for plasma samples were 70 and 40%. The monoclonal nonspecific-antibody assay produced results 10% to 140% higher than polyclonal-assay results, depending on sample matrix and transplant indication; the largest difference was seen in samples from heart- and liver-transplant recipients. Evidently the specific-antibody assay provides a convenient alternative to high-performance liquid chromatography for specific measurement of the drug, but the role of the new nonspecific antibody, possessing an even broader spectrum of cross-reactivity with cyclosporine metabolites than the original polyclonal antiserum, has yet to be defined.

Study of the conformation of cyclosporine in aqueous medium by means of monoclonal antibodies

The three-dimensional structure of the immunosuppressive cyclic peptide cyclosporine (Cs), determined in crystal by X-ray analysis and in solution in aprotic solvents by n.m.r., differs mainly by the orientation of the 7 carbon side chain of residue 1. Because of its poor solubility in water, the conformation of Cs in aqueous medium cannot be studied by n.m.r. methods, which require concentrations of the substance of the order of milligram/mL but can be analyzed by immunochemical methods in which concentrations in the nanogram/mL range are detected. In the present study, the ability of a series of monoclonal antibodies (McAbs) raised against Cs to recognize different parts of residue 1 of Cs was determined from the cross-reactivity of different Cs-analogues modified in residue 1. The results show that when Cs is dissolved in aqueous buffer, the terminal atoms of residue 1 side chain are not available for binding to antibodies recognizing the face of the molecule defined by residues 1, 2, 3, 10, 11, suggesting that the chain is probably folded back under the molecule, as observed in the crystal structure. Binding of McAbs to Cs was also affected by conformational modifications of the peptide ring that occur in some Cs-analogues. The results illustrate the potential of McAbs for probing the conformation of Cs-derivatives for which no structural data are available.

Controlled trial of azathioprine and cyclosporin to prevent anti-HLA antibodies due to third-party transfusion

The beneficial effect of elective transfusion on renal allograft survival must be weighed against the risks of sensitisation. We report a randomised controlled trial in which patients in end-stage renal failure who were non-parous and not previously transplanted or transfused, were entered in a transfusion protocol during which one group received no drugs (controls), one received azathioprine, and one received cyclosporin. Each group was given three identical transfusions of leucocyte-enriched fresh blood at 2-3 week intervals. The transfused blood was of known HLA type and donor/recipient pairs were completely mismatched. Sensitisation rates were assessed by T and B cell cross-matches between donor and recipients and by the screening of all sera against lymphocytes from 40 random donors. Fifty-one patients have completed the protocol, 20 in the control group, 12 in the azathioprine group, and 19 in the cyclosporin group. The sensitisation rate in the control group was 30%, occasionally of high titre, and persistent. In the azathioprine group, 25% developed anti-HLA antibodies and reactivity was of high titre and was broadly specific. Sensitisation in the cyclosporin group was 10%, was narrowly specific, reacting with only 10% of a panel, and was transient. There was no difference in graft survival between the groups. We conclude that cyclosporin therapy concurrent with third-party transfusion reduces the incidence, titre, and duration of sensitisation.

Twenty years of heart transplantation at Groote Schuur Hospital

Between December 1967 and July 1987, 110 heart transplantations (61 heterotopic and 49 orthotopic) and 12 heart-lung transplantations were done at Groote Schuur Hospital in Cape Town, South Africa. Twelve procedures were retransplantations, including two third interventions. The patients were divided into three groups: Group A (n = 55) from 1967 to 1982 received so-called conventional treatment of azathioprine, methylprednisolone, and antithymocyte globulin. Group B (n = 15) from 1983 to 1984 had cyclosporine in high dosages together with methylprednisolone. Group C (n = 30) received quadruple drug therapy of low-dosage cyclosporine, together with azathioprine, methylprednisolone in lower dosages, and antithymocyte globulin (for the first 4 to 6 days and rescue antithymocyte globulin for severe rejection). From Group A, nine of 55 patients are alive up to 17 years after transplantation. The main causes of death were acute rejections and infections (in 60% altogether). From group B, six of 15 patients are alive. Acute rejections and infections were the causes of death in 12% of the patients, but multiple organ failure was a major cause in 24% most probably because of the high dosages of cyclosporine. From group C, 23 of 30 patients have survived. In this group the results after heterotopic heart transplantation do not differ significantly from orthotopic transplantation, which justifies this procedure in particular situations. If all heterotopic and orthotopic transplantations are compared, orthotopic procedures have a substantially better outcome. With the modified immunosuppressive regimen (group C) combined with precise donor and recipient selection and more sophisticated rejection monitoring, the actuarial survival rate within the last 12 months is 94%.

Fine specificity and cross-reactivity of monoclonal antibodies to cyclosporine

More than 180 monoclonal antibodies (McAbs) to the cyclic undecapeptide cyclosporine (Cs) have been prepared. Several immunization protocols and antibody screening processes were compared. Two main groups of McAbs recognizing different "sides" of the Cs molecule could be differentiated. The antibodies belonged to the IgG and IgA classes and showed high affinity for Cs (up to 10(-10) -10(-11) mol/l). Based on their ability to discriminate Cs-derivatives modified singly at each of the 11 residues of the Cs molecule, the antigenic recognition pattern of different McAbs was studied at the level of individual residues. Closely related recognition patterns were found in each of the two main McAb groups. The apparent size of the Cs antigenic sites recognized by different McAbs varied from four to ten residues and did not correlate with antibody affinity.

The effect of immunosuppressants and adoptive transfer in monocrotaline pyrrole pneumotoxicity

Monocrotaline pyrrole (MCTP) is a pyrrolizidine alkaloid that causes pulmonary vascular injury and pulmonary hypertension in rats. The lesions in lungs of MCTP-treated rats are similar to those occurring in humans with primary pulmonary hypertension. Thus, the MCTP-treated rat is a good animal model for this disease. The mechanisms by which MCTP causes lung injury are unknown. The character of the pulmonary lesions and the delay in onset of the injury after a single low dose of MCTP suggest that immune mechanisms may be important in the pathogenesis. Accordingly, rats were treated with MCTP and the immunosuppressants antilymphocyte serum (ALS) or cyclosporin A (CyA). Neither ALS nor CyA completely protected rats from the injury due to MCTP. Several series of experiments also were undertaken to assess the effect of lymphocytes adoptively transferred from MCTP-treated donor rats into MCTP-treated recipient rats. Adoptive transfer of lymphocytes did not decrease the onset time of the injury or increase the severity of lesions due to MCTP in the recipients. These results indicate that immune mechanisms are probably not involved in MCTP-induced pulmonary injury.

Potential of monoclonal antibodies to improve therapeutic monitoring of cyclosporine

We show that monitoring of cyclosporine by immunoassay could be improved by using monoclonal antibodies (MAbs) of restricted specificity instead of polyclonal antisera that recognize both unmodified cyclosporine and its metabolites. MAbs with high affinity for cyclosporine have been prepared and characterized. We tested their ability to discriminate between native cyclosporine and its metabolites in indirect solid-phase enzyme immunoassay with a set of cyclosporine metabolites modified at residues 1, 4, 6, and 9 (corresponding to the six known sites of metabolism of cyclosporine). All the metabolites tested were detected by MAb1 at least 15- to 1000-fold less well than unmodified cyclosporine. A second MAb recognized unmodified cyclosporine and most of its metabolites equally well. Both MAbs retained their activity when coupled to alkaline phosphatase and could therefore be used in a direct solid-phase enzyme immunoassay.

Cyclosporine: immunology, pharmacology and therapeutic uses

Human and animal investigations since the mid-1970s have demonstrated the effectiveness of cyclosporine (CsA) as an immunosuppressive agent. In the area of transplantation immunity, it has been shown to enhance success of renal, bone marrow, and liver transplantation. Moreover, certain models of autoimmune disease have been effectively treated with CsA, and a number of studies have reported encouraging results with CsA therapy for ocular inflammatory disorders, notably Behçet's disease. The most serious side effects of CsA are nephrotoxicity and hypertension; thus, conservative dosages of the drug and careful monitoring of renal function during treatment are recommended. The purpose of this review is to provide clinicians and researchers with a clear perspective of both the potential benefits and shortcomings of this agent.

Diminishing morbidity and mortality of bone marrow transplantation

The reasons for the operational failure of bone marrow transplantation (BMT) are familiar and varied. They are the following: nonmarrow toxicity of the preparative regimen, marrow toxicity of the preparative regimen, acute graft-versus-host disease (GVHD), opportunistic infections, especially viral infections and recurrence of hematologic malignancy in the case of transplants for leukemia. This review examines operational failure of BMT and presents measures for its prevention.

Exogenous IL2 partially reverts CML non-reactivity acquired during prophylactic immunosuppression with cyclosporin A of human allograft recipients

Proliferative and cytolytic lymphocyte responses and the influence of exogenous interleukin 2 (IL2) on cell-mediated lympholysis (CML) reactivity were evaluated in 12 allograft recipients. Responses were induced by mitogenic lectins or by donor and third-party cells. Patients were tested immediately before transplantation (Tx) and one and three months after grafting. Prophylactic immunosuppression consisted of Cyclosporin A (CyA) and low-dose prednisone (P). Analysis of post transplant cells revealed a reduced overall proliferative T cell responsiveness induced by both alloantigens and mitogenic lectins. No evidence for donor-specific reduction of MLC responses was seen. Overall CML reactivity of post-Tx lymphocytes was also impaired. This was accompanied by donor-specific CML non-reactivity in six of seven patients with quiescent grafts. In these patients, the cytolytic potential against donor cells could be restored when maximal T cell help via exogenous IL2 was provided.

Effects of cyclosporin A on the activity of mouse natural killer cells and hybrid resistance

It was found that a single dose of cyclosporin A (CSA) administered intraperitoneally resulted in rapid, but transitory reduction of (C57B1/6 X DBA/2)F1 spleen cell natural killer (NK) activity (on day 1 after CSA), then a return to the normal level (on day 3 after CSA) and finally gradual, but sharp decrease of this activity (the lowest activity on day 9). It was also found that CSA injected 3 days before semi-allogenic bone marrow transplantation (BMT) has no effect on hybrid resistance (HR), but administered 9 days before BMT caused abrogation of HR. So, there was a correlation between changes of NK activity after CSA and effects of CSA on HR, suggesting that NK cells are responsible for HR. In contrast, there was no effect of CSA on the engraftment of syngeneic bone marrow cells.