The experimental and clinical use of immune-modulating drugs in the prophylaxis and treatment of infections

Therapeutic agents capable of stimulating immune responses could be of great value in the prophylaxis and treatment of infectious diseases. Three classes of compounds, each representing a separate approach to the goal of immune stimulation, are discussed with respect to recent experimental and clinical findings. The action of microbial structures and their derivatives can be understood on the basis of "acquired cellular immunity", a phenomenon first described in connection with infections by mycobacteria and other intracellular organisms. In contrast, there is hardly a common denominator for synthetic compounds which are currently used as immune-stimulatory agents. Substances which influence purine metabolism in lymphocytes on the one hand and histamine H2 blockers such as cimetidine on the other hand seem to represent the most promising developments in this field to date. Products of immune cells such as transfer factor and lymphokines form the third and possibly most important group of immune-stimulating agents. Current experimental and clinical trends in this field are briefly described. It is suggested that the delineation of the mechanism of action of lymphokines will open the door to the identification or synthesis of artificial agonists and antagonists as has been the case in the pharmacology of the endocrine and nervous systems.

[Analysis of prognostic factors in plasmacytoma]

For analysis of prognostic factors the clinical course of 109 patients with multiple myeloma was evaluated. Survival curves of immunoglobulin (Ig)G- and IgA-myelomas were identical (Fig. 1) with median survival times of 52 and 42 months, respectively, whereas patients with IgD- and Bence-Jones-myeloma had short survival times (median 3 months). Most important risk factors were anemia, renal insufficiency, and hypercalcemia (Figs. 7 and 8). Median survival time dropped from 52 months (Hb above 100 g/l) to 22 (Hb 85-100 g/l) and 1 month (Hb below 85 g/l). Patients with serum creatinine values below 2 mg/dl lived significantly longer than those with values above. Median survival times were 52 and 1 month, respectively. All seven hypercalcemic patients had a renal insufficiency and were in a very poor condition; their median survival time was 1 month. Analysis of the widely used staging system of Durie and Salmon gave disappointing results. Survival curves of the three A-stages ran close together with median survival times of 58, 51, and 36 months. Only the A-B classification according to renal function (A: creatinine under 2 mg/dl; B: creatinine above 2 mg/dl) proved prognostically relevant.

Immunostimulation. Clinical and experimental perspectives

Three classes of immunostimulating drugs are described, each representing a different approach to the problem of pharmacological immunostimulation. The rationale for the use of microbes or microbial agents as immunostimulators rests on the fact that some micro-organisms, especially those that replicate intracellularly, carry a special potential to activate macrophages. Clinically, the use of these agents in patients with tumors and infections has been disappointing; however, there have been positive exceptions like the responsiveness of melanomas and bladder carcinomas to the injection of BCG. Many of the inconclusive results may be due to insecurities in the dosage of microbial preparations and to a general lack in standardization. Some structures with high efficacy and low toxicity which have recently evolved from this field deserve further investigation. A number of structurally unrelated synthetic compounds was found to influence immune parameters. Levamisole can today be classified as an immunostimulating drug with limited utility in recurring infections and in chronic polyarthritis. Several immunostimulating drugs which have attracted interest contain a purine as the effective component. This is not surprising in view of the fact that many genetically determined immunodeficiencies can be traced to defects of enzymes which play a crucial role in purine biosynthesis. Finally, the potential role of lymphokines as stimulators of the immunosystem is briefly described. Some of these glycoproteins have recently become available for clinical trials. Others will be made available through genetic engineering. The therapeutic utility of these compounds is not yet clear; they will, however, be of great value as probes for the study of immune functions and for the development of immunopharmacology.

The experimental and clinical use of immune-modulating drugs in the prophylaxis and treatment of infections

Therapeutic agents capable of stimulating immune responses could be of great value in the prophylaxis and treatment of infectious diseases. Three classes of compounds, each representing a separate approach to the goal of immune stimulation, are discussed with respect to recent experimental and clinical findings. The action of microbial structures and their derivatives can be understood on the basis of "acquired cellular immunity", a phenomenon first described in connection with infections by mycobacteria and other intracellular organisms. In contrast, there is hardly a common denominator for synthetic compounds which are currently used as immune-stimulatory agents. Substances which influence purine metabolism in lymphocytes on the one hand and histamine H2 blockers such as cimetidine on the other hand seem to represent the most promising developments in this field to date. Products of immune cells such as transfer factor and lymphokines form the third and possibly most important group of immune-stimulating agents. Current experimental and clinical trends in this field are briefly described. It is suggested that the delineation of the mechanism of action of lymphokines will open the door to the identification or synthesis of artificial agonists and antagonists as has been the case in the pharmacology of the endocrine and nervous systems.

In vitro activity of naftifine, a new antifungal agent

Naftifine exhibits an interesting in vitro spectrum of activity against dermatophytes (38 strains; minimal inhibitory concentration [MIC] range 0.1 to 0.2 microgram/ml), aspergilli (6 strains; MIC range, 0.8 to 12.5 microgram/ml), Sporothrix schenckii (2 strains; MICs, 0.8 and 1.5 microgram/ml), and yeasts of the genus Candida (77 strains; MIC range, 1.5 to greater than 100 microgram/ml). Its degree of efficacy is unaffected by the organism density in the test medium, and it is primarily fungicidal against dermatophytes as well as yeasts. Its in vitro efficacy is pH dependent and rises with increasing pH values.

[Clinical trial in couples of effectiveness and side-effects of gold and D-penicillamine in long term treatment of rheumatoid arthritis (author's transl)]

A prospective clinical trial in couples was done to compare effectiveness and toxicity of gold and D-penicillamine (D-Pen.) in treatment of rheumatoid arthritis (r.A.). Respecting defined criteria 70 patients were put to couples according to a random list and were treated with gold or D-Pen. alternatively. Physical and laboratory indices of inflammatory activity were checked every 3 months, X-rays every 12 months. Dropouts (side effects, missing compliance, uneffectiveness) were replaced by the nextcoming fitting patient. Thirty-two of 147 totally recruited patients stopped treatment because of side effects, three because of unsatisfying efficiency. Forty-two patients shuned the necessary controls. The clinical course was better in 16 couples with gold, only in sex couples with D-Pen. Thirteen pairs showed no difference in this respect (p = 0.05). Looking to the laboratory parameters separately D-Pen. tends to be superior (p < 0.05), radiografic deterioration seems to be more seldom with gold (< 0.05). Side effects occur with both drugs in comparable frequency (15/44 with D-Pen., 17/52 with gold), but the complications with D-Pen. are more serious. Altogether this trial shows gold superior to D-Pen. in the long-term treatment of r.A.

Inhibition of mitogen-induced lymphokine production by cyclosporin A

The new antilymphocytic agent Cyclosporin A was found to inhibit the production and/or secretion of migration inhibitory factor (MIF) in human lymphocytes stimulated by Concanavalin A. Preincubation for one hour with the compound, followed by 8 hr restoration period of the cells in absence of the drug, resulted in moderate decrease in MIF synthesis and/or release. Cell viability was not affected. The agent was shown not to interfere with MIF action on the macrophage. We conclude that the molecular mechanism of action of Cyclosporin A is based, at least partially, on a blockade of synthesis and/or secretion of lymphokines from immunocompetent cells.

Differential analysis of selected prompts and neurological variables in motor assessment of moderately mentally retarded children

The purpose of this study was to elevate the specificity of gross-motor assessment strategies presently used with moderately mentally retarded children by measuring voluntary motor performance as a function of level of reflex development, level of orthopedic functioning, and type of prompts used in test instructions. After clinically assessing subjects' levels of reflex and orthopedic functioning, we randomly assigned subjects to multisensory-, physical-, modeling-, and verbal-prompt treatment groups. Multisensory prompts and differential use of selected prompts were effective with younger and older children, respectively. A significant interrelationship was found between subjects' levels of reflex development and voluntary motor performance.

The effect of a protein-bound polysaccharide from Coriolus versicolor on immunological parameters and experimental infections in mice

The influence of PSK, a protein bound polysaccharide from Coriolus versicolor on various immunological parameters was studied, PSK was found to enhance B cell activity as measured by the spleen plaque-forming cell assay in mice, and to stimulate mouse macrophages as determined by an enhancement of carbon clearance and an increase in the phagocytosis of opsonized sheep red blood cells by peritoneal mouse macrophages in vitro. The activation of mouse macrophages by PSK appeared to correlate with the therapeutic effects of the compound. In mice made granulocytopenic with cyclophosphamide and subsequently infected with a variety of garm-negative pathogens or with Candida albicans, PSK prolonged the average survival time of the animals. The compound also led to a drastic increase in the number of animals surviving such experimental infections as compared to untreated controls. Possible mechanisms responsible for these protective effects by PSK are discussed.

The isolation and characterization of elongation factor eEF-Ts from Krebs-II mouse-ascites-tumor cells and its role in the elongation process

A factor having activity similar to that described in other systems for the eukaryotic elongation factor eEF-Ts was isolated from the heavy, aggregate form of eEF-TH (formally named EF-1H). This protein has a molecular weight of 52000 under native conditions and of 25500 under denaturing conditions. It has been shown to stimulate eEF-Tu-dependent aminoacyl-tRNA binding to ribosomes and therefore eEF-Tu/eEF-G-dependent polyphenylalanine synthesis by ribosomes and was found to stimulate GDP-GTP exchange in eEF-Tu . GDP complexes. In the course of this work, it was also demonstrated that the removal of deacylated tRNA from the ribosome is a GTP-dependent process. This report, therefore, adds further support to the concept that a third elongation factor, eEF-Ts, may be common to all systems in the eukaryotic domain.

Nonspecific resistance to bacterial infections. Enhancement by ubiquinone-8

A lipid fraction from Escherichia coli was extracted with apolar solvents and was found to protect mice from a number of experimental bacterial infections. The benzoquinone, ubiquinone-8, was isolated from this extract by high pressure liquid chromatography and identified as such by nuclear magnetic resonance and mass spectrometry. At a dose of 25 mg/kg this substance was found to provide complete protection against otherwise lethal infections with gram-negative and gram-positive bacteria in mice. Treatment was most effective when given intravenously 24 h before infection. In comparative studies, ubiquinone-8 had a clearly higher activity than ubiquinones-4, Q6, and Q10. A highly significant increase in the clearance rate of bacteria from the blood by the spleen and the liver of treated animals, correlated well with the protective effect of ubiquinone-8. The compound stimulated the ability of mouse macrophages to incorporate sheep erythrocytes and significantly increased the number of antibody-producing cells in spleens of mice.

Further evidence that elongation factor 1 remains bound to ribosomes during peptide chain elongation

This paper describes three types of experiments which indicate that the binding sites for elongation factor 1 (EF-1) and elongation factor 2 (EF-2) on ascites cell ribosomes are not identical and perhaps not even overlapping. The experimental evidence presented includes direct competitive binding of labeled elongation factors to ribosomes as well as the influence of pokeweed antiviral protein and Escherichia coli anti L7/L12 proteins on the binding and function of the two factors. It is further shown that EF-1beta from Artemia salina does not function in displacing EF-1 from mouse ascites tumor cell ribosomes. These results also support our recently proposed model that EF-1 remains bound to the ribosome during the peptide chain elongation cycle.

A new concept of the function of elongation factor 1 in peptid chain elongation

An entirely new model for the mechanism of elongation factor 1 (EF-1) function is presented. Experiments in which mixtures of [3H]EF-1, ribosomes from Drebs II ascites cells and various additional co-factors were analyzed by chromatography on Sepharose 6B, show that EF-1 binds to the ribosome early in the translation process and remains bound on the ribosome during translation. Optimal EF-1 binding occurs on polynucleotide-programmed ribosomes carrying a tRNA in their P-site. On the other hand it was clearly shown that EF-2 attached at each translocation event and was then released before a new Phe-tRNA could be bound.

Functional identity of the monomeric and multiple forms of elongation-factor 1 from Krebs-II mouse ascites-tumor cells

Highly purified 3H-labelled elongation factor 1 (EF-1) from Krebs II mouse ascites tumour cells was separated into biologically active monomeric and aggregate forms of the enzyme by either gradient centrifugation or gel filtration. When corrected for their content of inactive enzyme both forms of the factor were found to be equally active whether tested in the binding or synthesis reaction. The only form of the enzyme found bound to ribosomes was the monomer; it was therefore concluded that the aggregate form of the enzyme must first dissociate before it reacts with the ribosome. The stoichiometry of the aminoacyl-tRNA binding reaction to ribosomes in the presence of guanosine nucleotides was also studied. It was found that one molecule of aminoacyl-tRNA and of Guo-5'-P2-CH2-P is bound per molecule of EF-1 bound to the ribosome. Following interaction with a release from, the ribosomes, EF-1 was found to be predominantly monomeric.

Parameters of acquired resistance and their role in the evaluation of new chemotherapeutic drugs

Acquired resistance can be defined as a qualitative alteration of the genetic material of a cell which is phenotypically correlated with a measurable decrease of the cell's sensitivity against one or several chemotherapeutic agents. There are two basic genetic mechanisms which can lead to the emergence of resistance: mutation and the acquisition of additional genetic material from another cell. Both forms of resistance play an important role in clinical situations: the emergence of resistance by mutation occurs in tumor cells and can also lead to therapeutic problems in antimicrobial chemotherapy. In bacteria, however, acquisition of resistance plasmids represents the dominating mechanism which is responsible for most therapeutic problems in the clinical environment. The different genetic mechanisms involved in the emergence of resistance are paralleled -- at least in bacteria -- by two principally different groups of biochemical mechanisms implementing resistance. Mutations lead to alterations of single cell constituents such as the cell membrane or cellular receptors necessary for the binding of the antimicrobial agent. This form of resistance is biochemically characterized by the inaccessibility of the cell interior for a particular compound or by the modification of an intracellular binding site which loses its affinity for the chemotherapeutic agent. Resistance plasmids on the other hand code for enzymes which inactivate the antibiotic (beta-lactamases, aminoglycosideinactivating enzymes, chloramphenicol-acetyltransferase); In some cases, they direct the synthesis of proteins which affect cell permeability (tetracycline) or isoenzymes which have a lower affinity for the inhibitor (trimethoprim). Resistance against antibiotics can be inducible; In these cases the regulatory mechanisms involved are stable genetical traits as resistance itself; Using chloramphenicol, beta-lactam-antibiotics and aminoglycosides as examples, it is demonstrated that resistance data gathered early in the development of a new drug are of little value in estimating the clinical potential of a new compound. Information on the rate at which resistance develops, on the pattern according to which it emerges ("single step" or "multi step") and on cross-resistance patterns is important in the characterization of a new drug but is often invalidated by later findings obtained in the clinical environment; The problem appears somewhat simpler if a new drug is a member of an already known class of compounds, e.g. a beta-lactam or an aminoglycoside. In such cases our knowledge of frequent enzymatic inactivation mechanisms provides a basis not only for the evaluation of an existing drug, but also for the synthesis of new derivatives.

The binding of tritiated elongation-factors 1 and 2 to ribosomes from Krebs II mouse ascites-tumore cells. The influence of various antibiotics and toxins

The effect of a number of different antibiotics and toxins on the capacity of Krebs II mouse ascites ribosomes to bind 3H-labelled elongation factors (EF-1 and EF-2) has been examined. It was found that abrin and ricin inhibit the binding of EF-2, while diphtheria toxin, sparsomycin, streptovitacin A, and cycloheximide had essentially no effect on its binding. Of the other compounds examined, sparsomycin was unique in its capacity, under some circumstances, to significantly affect the binding of aminoacyl-tRNA and EF-1 to ribosomes. Fusidic acid appears to nonspecifically enhance the binding of both EF-1 and EF-2.

Effect of active and passive immunizations with lipid A and salmonella minnesota Re 595 on gram-negative infections in mice

The capacity of lipid A, a structure common to the lipopolysaccharide cores of all gram-negative bacteria, to serve as an active immunizing agent in mice and to protect these animals against gram-negative infections was investigated. Active immunization experiments were also performed with the Re mutant of Salmonella minnesota 595 which carries a lipopolysaccharide composed of lipid A and three residues of ketodeoxyoctonic acid. Single injections of lipid A complexed to acid-hydrolyzed bacteria as carriers failed to induce specific protection against subsequent challenge infections with E. coli O4 and S. breslau. Repeated injections of lipid A resulted in good protection against intraperitoneal challenge with S. breslau and partial protection against intravenous challenge with the same organism but did not alter the sensitivity of mice to challenge infections with E. coli or Pasteurella multocida. Whole antisera or serum fractions from rabbits in which high titers against lipid A had been attained by repeated intravenous injections of the antigen did not protect mice against challenge infections with E. coli O4. In contrast a single injection of the Re mutant of S. minnesota antigen in combination with incomplete Freund's adjuvant provided substantial protection against an otherwise lethal intraperitoneal infection with S. breslau over a period of at least 45 days. Repeated application of the Re antigen resulted in partial protection against experimental infections with E. coli O4, S. breslau and Pasteurella multocida. Injections of S. minnesota Re 595 antiserum provided better protection against an E. coli O4 infection than lipid A sera or antibodies of the IgG or IgM type directed against this antigen.