Drug-induced antibodies during 2-N-methyl-9-hydroxyellipticinium acetate (NSC-264137) treatment: schedule dependency and relationship to hemolysis.

Drug-dependent antibodies were investigated in patients treated with elliptinium acetate, a cytostatic drug with activity in advanced breast cancer. Retrospective analysis of 83 patients, receiving weekly intravenous elliptinium, showed a high incidence of anti-elliptinium antibodies (20%). Hemolysis occurred among antibody-positive patients, apparently related to the antibody titer. The predictability of anti-elliptinium antibodies for hemolysis and the schedule dependency of antibody development was examined prospectively. Among 42 patients treated weekly for at least three courses, 40% developed antibodies. Of 30 patients receiving elliptinium daily for three days every three weeks, none developed either antibodies or hemolysis. Only antibody positive patients, with titers greater than or equal to 32 were at risk for hemolysis. The possible mechanisms are discussed.

Monoclonal antibodies to lipophilic and short-sized haptens: application to the 4-amino-quinoline antimalarial drugs.

Monoclonal antibodies recognizing the 4-amino-7-chloro-quinoline (ACQ) structure, which represents the backbone of the 4-amino-quinoline antimalarial drugs, were obtained in mice, after injection of ACQ coupled to hemocyanin via the glutaraldehyde method. The resulting antibodies show a definite specificity to this hapten, but react better with compounds substituted on the exocyclic amino group in 4. It is postulated that the quinoline ring is not sufficient for the reaction with the antibodies, and that an enlarged structure, which is given by the bridge used to link hapten and carrier, entails an important increase (1000-fold) in the apparent affinity. The striking similarities between this bridge and the lateral chains of the antimalarial drugs are accountable for this enhanced recognition. This result allows us to indicate that in some instances, the bridge-structure of the immunogen should be positively involved in the epitope. This observation may become useful in the conception of immunogens, aiming to obtain antibodies directed against some lipophilic and small-sized haptens.

The immune response to a synthetic peptide analogous to the 109-145 beta hCG carboxyl-terminus is directed against two major and two minor regions.

The immune response to a 37-amino acid synthetic peptide analogous to the carboxyl-terminal part (109-145) of the human chorionic gonadotropin beta subunit (beta hCG) was studied with monoclonal antibodies selected from 31 cell fusion experiments. Analysis of the immunogenic determinants borne on the synthetic peptide (CTP) showed a prevailing response to two immunodominant regions. The first was located on the 110-116 amino acid sequence of the CTP which is also the most hydrophilic region: 50% of anti-CTP antibodies selected for their high binding to 125I beta hCG were directed to this sequence. A second immunodominant portion was recognized by four antibodies, and comprised amino acids 134 to 139, representing a highly O-glycosylated region on the native protein. Moreover, a unique antibody designated FB13 bound to a region located on the last seven amino acids (139-145) of beta hCG. Finally, a hypothetical conformational determinant was recognized by antibody FB02 within the 121-145 region. Thus, the immune response to CTP was directed against two major and two minor regions. These antigenic determinants were demonstrated to be accessible for antibody binding on both the hCG molecule and its beta subunit. Localization of these epitopes suggests a relationship between the hydrophilicity and the immunological potency of different CTP regions.

Biochemical, behavioral, and electrophysiologic actions of the selective sigma receptor ligand (+)-pentazocine.

Research on the sigma receptor, a binding site associated with drug-induced psychotomimetic behaviors, has been hampered because most sigma agonists also interact with the phencyclidine (PCP) receptor. (+)-Pentazocine, a human psychotogen, is a selective sigma receptor ligand. To demonstrate sigma receptor activities, we studied the behavioral and electrophysiologic actions for (+)-pentazocine. In the behavioral drug discrimination procedure in which rats were trained to discriminate between 2.0 mg/kg (5.59 mumol/kg) (+)-pentazocine and saline, (+)-pentazocine produced dose-related increases in the percentage of trials completed on the (+)-pentazocine lever. At a dose of 1.0 mg/kg (3.29 mumol/kg) (+)-N-allylnormetazocine generalized completely to (+)-pentazocine. By contrast, PCP only partially generalized. In the visual evoked potential test, these compounds produced a significant dose-dependent slowing of the N2 latency. This response was prevented by haloperidol pretreatment. These results demonstrate pharmacologic actions for the selective sigma receptor ligand (+)-pentazocine and suggest some overlapping pharmacologic properties of the sigma and PCP receptor sites despite differences in central nervous system distribution.

Antibody recognition of substituted ammonium ions. Modulation by the counterion.

Antibodies directed against elliptinium acetate, a quaternary ammonium compound with antineoplastic activity in man, were obtained in rabbits, after conjugation of the drug with haemocyanin. These antibodies are specific for the quaternary ammonium structure. However, the recognition of the drug can be markedly decreased (ten-fold) by changing the associated counterion. These observations were extended to other ellipticine derivatives that exist in two forms: acetate and chloride. In each case, the recognition of the acetate form was 7-11-fold higher than that of the chloride form. These results could be explained by high-energy strengths existing between the cation and the anion, resulting in a paired-ion antigen. This represents the first identification of antibodies directed to a paired-ion structure, with specificity for both the cation and anion used for immunization. Such results are relevant in the construction of immunoassays for quaternary ammonium compounds.

Radioiodination of human calcitonin using the Iodogen reagent.

A method is described for the radioiodination of human calcitonin using the Iodogen reagent. The tracer was purified by 2 successive gel filtrations. The first, using Sephadex G-10, resulted in the complete removal of free 125iodide as assessed by ascending paper chromatography. The second, involving Sephadex G-75, permitted the separation of the tracer from high molecular weight aggregates. Analytical RP-HPLC showed a slight proportion (13%) of a contaminating product, probably (sulfoxyl-methionine9)calcitonin. The final yield, after radioiodination, was found to be 42.7 +/- 5.5% and the tracer displayed a specific activity of 850 +/- 110 Ci/mmol. The effects of long-term storage of the frozen tracer were studied.

Ellipticine derivatives interact with muscarinic receptors.

Ellipticine derivatives or analogues, tetracyclic alkaloids used in human cancer treatment, have been evaluated with regard to their interaction with several neurotransmitter receptors, in order to explain or to predict the side effects which occur in man. These drugs were recently found to be reversible non-competitive inhibitors of cholinesterases. In this study, we have shown that ellipticines are also potent muscarinic antagonists, only 100-fold less active than atropine in inhibiting 50% of the specific binding of (3H) quinuclidinyl benzilate on rat brain preparation of muscarinic receptors. That the interaction with muscarinic receptors is quite unique has been demonstrated by the lack of interaction with three other neurotransmitter receptors. Tertiary amines show relatively less blockade of muscarinic receptors, while substituted ammonium ions are better inhibitors of the QNB binding. The possible mechanisms of in vivo action of these alkaloids is discussed.

Evaluation of a new preservation solution: Celsior in the isolated rat lung. Paris-Sud University Lung Transplatation Group.

BACKGROUND: We compared Celsior solution, a new and original extracellular preservation solution, with blood-based Wallwork's solution. METHODS: In two groups of isolated rat lungs submitted to 4 hours of cold ischemia, pulmonary arterial and venous resistances, coefficient of filtration, and wet-to-dry lung weight ratio were determined at baseline and after 90 minutes of reperfusion. RESULTS: After ischemia-reperfusion, percentage of increases above the respective baseline coefficient of filtration values were 93% +/- 7% in the Wallwork group and 7% +/- 3% in the Celsior group (p < 0.001 versus Wallwork's solution). CONCLUSIONS: These results show that Celsior consistently prevented the ischemia-reperfusion-induced increase in pulmonary microvascular permeability as compared with Wallwork's solution.

Efficacy of lactobionate-enriched cardioplegic solution in preserving compliance of cold-stored heart transplants.

Cardioplegic solutions of the extracellular type are commonly used as storage media for heart transplants. Because this type of formulation was not originally designed for preventing hypothermically induced edema, we assessed the effects of supplementing a standard, extracellular-like cardioplegic solution with the high molecular weight impermeant lactobionate on water content and postischemic compliance of isolated rat hearts. In one series of experiments, hearts were immersed in either a standard cardioplegic solution of the extracellular type or in the same solution supplemented with lactobionate (80 mmol/L). Hearts were then processed for measurements of water content after 4 hours, 6 hours, and 8 hours of storage at 4 degrees C. In a second series of experiments, hearts were stored in the same solutions for 4 hours and 8 hours and subsequently reperfused for 1 hour on a Langendorff column, at which time left ventricular pressure-volume curves were constructed and compared with those obtained during the preischemic perfusion. Lactobionate-treated hearts gained significantly less water than controls after 4 hours and 6 hours of storage, but the difference was no longer significant at the 8-hour time point. In contrast, the treated group yielded a significantly better recovery of compliance after both 4 hours and 8 hours of storage, suggesting that lactobionate might exert protective effects in addition to those caused by its impermeant properties, possibly involving calcium chelation and subsequent limitation of calcium-dependent contracture. Extracellular-type cardioplegic solutions are attractive because a single solution can be used during all phases of the transplantation procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

A dose-searching trial of an anti-LFA1 monoclonal antibody in first kidney transplant recipients.

25.3, a mouse IgG1 monoclonal antibody (MoAb), directed at the alpha chain of the LFA1 molecule (CD11a) has been used in prophylaxis of rejection in recipients of cadaveric kidney graft. Promising clinical results have been obtained for both tolerance and efficacy [1]. The aim of this trial was to determine the optimal dosage, base on a pharmacokinetic-pharmacodynamic analysis of the data obtained from the 15 patients included in this dose-searching study. Biological parameters, such as circulating levels and functional inhibition (as detected in an adhesion assay of patient lymphocytes), were measured during and after treatment. A Hill relation was calculated between the effect and the concentration measured and led us to select a 15 mg/day dose for further clinical trials, with a loading dose of 30 mg. An additional group receiving this protocol was submitted to the same calculation, and the results from this last group were in agreement with this previous analysis.

Characterization of a peripheral-type benzodiazepine binding site on human circulating lymphocytes.

Binding studies conducted with [3H]Ro 5-4864, a specific ligand for peripheral-type benzodiazepine receptors, on circulating lymphocytes from 5 normal volunteers provided evidence for a single, saturable (Bmax 12.2 +/- 3.6 fmol/10(6) cells), and high affinity (KD 7.1 +/- 2.0 nM) specific binding site. We were unable to detect any GABA receptor, suggesting that human lymphocytes bear a peripheral-type benzodiazepine binding site not coupled with the GABA system. Results on lymphocytes from chronic lymphocytic leukemics are also reported.

In vivo modulation of muscarine receptors in rat brain by acute lead intoxication.

In our experiments on acutely lead exposed rats we observed a marked increase (a 2-fold or 3-fold increase with 30 mg/kg or 60 mg/kg lead acetate, respectively) in [3H]quinuclidinyl benzilate [( 3H]QNB) specific binding to muscarine receptors from striatum and cortex, without any change in receptor affinity. Muscarine receptor level was maximal 2 h after intoxication, but the effect of lead on [3H]QNB binding was completely reversible in 24 h, without any lead redistribution to other brain areas being observed during this time period. Modulation of muscarine receptors in rat brain during in vivo acute intoxication might be involved in some of the observed neurotoxic effects of lead, resulting of an action on cholinergic neurotransmission. The various possible mechanisms of the lead effect on [3H]QNB binding are discussed.

Benzodiazepine receptors on human blood platelets.

Binding studies conducted on membrane preparation from human platelets using (3H) Ro5-4864 and (3H) diazepam showed specific and saturable binding. Scatchard analysis revealed a single class of binding sites with KD = 10.8 +/- 0.9 nM and Bmax = 775 +/- 105 fmol/mg protein for (3H) Ro5-4864 and KD = 10.5 +/- 1.1 nM and Bmax = 133 +/- 19 fmol/mg for (3H) diazepam. We were unable to detect any GABA binding site on crude membrane preparation, nor did GABA enhance the binding of (3H) Ro5-4864 or (3H) diazepam. This suggests that benzodiazepine receptors are uncoupled to GABA system on human platelets. Ro15-1788, a specific antagonist for "central type" benzodiazepine (BDZ) binding sites was inactive in displacing (3H) Ro5-4864 from membrane receptors, while PK 11195 (a specific ligand for the "peripheral type" receptor) was the most potent of the drugs tested in inhibiting (3H) Ro5-4864 binding. These results indicate that human blood platelets bear "peripheral-type" BDZ receptor. Moreover, we could not detect any (3H) propyl beta carboline specific binding on platelet membranes. Results on benzodiazepine receptors on human circulating lymphocytes are also reported and similarity in pharmacological properties with platelet benzodiazepine receptors is suggested.

Experimental evaluation of Celsior, a new heart preservation solution.

An original heart preservation solution (Celsior) has been developed, the formulation of which has been designed to fulfil two major objectives: (1) to combine the general principles of hypothermic organ preservation with those specific for the myocardium, and (2) to offer the possibility of being used not only as a storage medium but also as a perfusion fluid during initial donor heart arrest, poststorage graft reimplantation and early reperfusion. The major principles addressed by the Celsior formulation include (1) prevention of cell swelling (by mannitol and lactobionate), (2) prevention of by the Celsior formulation include (1) prevention of cell swelling (by mannitol and lactobionate), (2) prevention of oxygen-derived free radical injury (by reduced glutathione, histidine and mannitol), and (3) prevention of contracture by enhancement of energy production (glutamate) and limitation of calcium overload (high magnesium content, slight degree of acidosis). Two experimental preparations were used: The isolated isovolumic buffer-perfused rat heart model and the heterotopic rabbit heart transplantation model. In isolated heart experiments, hearts were arrested with and stored in Celsior for 5 h at 4 degrees C and subsequently reperfused for 1 h. A similar protocol was used in the transplantation experiments except that the total ischemic time was approximately 1 1/2 h longer (corresponding to 6 h of storage followed by the 25 additional minutes of cold ischemia required for graft implantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics, foreign protein immune response, cytokine release, and lymphocyte subsets in patients receiving thymoglobuline and immunosuppression.

The pharmacokinetics and immune response to the rabbit IgG of rabbit antihuman thymocyte globulin, Thymoglobuline has been characterized. A cytokine release pattern of TNF alpha and IL-6 but not IL-1 beta and IFN chi has been demonstrated with the first and not subsequent doses. An effect on lymphocyte depletion of peripheral blood with major subset suppression has been shown to last more than the 3-month observation period in patients on a regimen of quadruple sequential immunosuppression.

ENTPD1/CD39 is a promising therapeutic target in oncology.

Regulatory T cells (Tregs) are a subpopulation of CD4(+) T cells that are essential for maintaining the homeostasis of the immune system, limiting self-reactivity and excessive immune responses against foreign antigens. In cancer, infiltrated Tregs inhibit the effector lymphocytes and create a favorable environment for the growth of the tumor. Although Tregs mediate immunosuppression through multiple, non-redundant, cell-contact dependent and independent mechanisms, a growing body of evidence suggests an important role for the CD39-CD73-adenosine pathway. CD39 ectonucleotidase is the rate-limiting enzyme of a cascade leading to the generation of suppressive adenosine that alters CD4 and CD8 T cell and natural killer cell antitumor activities. Here, we review the recent literature supporting CD39 as a promising therapeutic target in oncology. In vitro and in vivo experiments involving knockout models and surrogate inhibitors of CD39 provide evidence in support of the anticancer activity of CD39 inhibition and predict a favorable safety profile for CD39 inhibitory compounds. In addition, we report the ongoing development of CD39-blocking monoclonal antibodies as potential anticancer drugs. Indeed, CD39 antagonistic antibodies could represent novel therapeutic tools for selectively inhibiting Treg function without depletion, a major limitation of current Treg-targeting strategies.