The skin allergenic properties of chemicals may depend on contaminants--evidence from studies on coumarin.

BACKGROUND/AIMS: Positive patch tests are considered representative of a contact allergy to the tested chemical. However, contaminants and derivatives rather than the suspected chemical itself could be responsible for the allergic skin reactions. Here, we tested the importance of contaminants in the sensitizing and allergenic properties of coumarin in mice and humans. Coumarin, an ingredient in cosmetics and fragrances, was chosen as the reference chemical since conflicting results have been obtained regarding its ability to induce contact allergy. In some chemical preparations, this could be explained by the presence of coumarin derivatives endowed with allergenic properties. METHODS: In mice, three different coumarin preparations were tested in the local lymph node assay. In humans, we assessed the irritant and allergenic properties of highly pure coumarin in nonallergic and fragrance-allergic patients. RESULTS: Pure coumarin did not exhibit irritant or sensitizing properties in the local lymph node assay. In contrast, two other commercially available coumarins and three contaminants that were detected in these coumarin preparations were identified as weak and moderate sensitizers, respectively. In humans, pure coumarin was extremely well tolerated since only 1 out of 512 patients exhibited a positive patch test to the chemical. CONCLUSIONS: These results indicate that coumarin cannot be considered as a common contact allergen and further emphasize that purity of chemicals is mandatory for the assessment of their allergenicity.

RP 55778, a PAF receptor antagonist, prevents and reverses LPS-induced hemoconcentration and TNF release.

Platelet-activating factor (PAF) and tumor necrosis factor (TNF) are present in the plasma of animals injected with endotoxin (LPS). Furthermore, when exogenously administered to animals, PAF and TNF induce similar pathological effects. Thus, in order to explore a possible link between these two factors, the effects of a PAF receptor antagonist, RP 55778, and a glucocorticoid, dexamethasone, were studied on LPS-induced hemoconcentration in rats and on the release of TNF induced by exposing isolated murine macrophages to LPS. RP55778 administered either before or after LPS inhibited these endotoxin effects whereas dexamethasone was effective only when given prior to the LPS challenge. Additionally, in murine macrophages the strong TNF mRNA signal induced by LPS was abolished by RP 55778 and dexamethasone treatment. These results indicate that PAF and TNF can mediate the functional manifestations associated with endotoxemia and only RP 55778 appears to show potential for activity against an already established LPS response.

Immunomodulating and antitumor activities of a synthetic lauroyltripeptide (RP 56 142).

Lauroyltripeptide (RP 56 142) (N2-[N-(N-lauroyl-L-alanyl)-gamma-D-glutamyl]-L,L-2,6-diaminopimelami c acid) was shown in murine models to activate several immune mechanisms involved in host defense against tumors. RP 56 142 induced macrophage activation and enhanced cytotoxicity of natural killer cells in spleen, blood, and liver. These activities correlated with prophylactic and therapeutic effects of RP 56 142 on artificial liver metastases of M5076 histiocytosarcoma. RP 56 142 alone did not inhibit spontaneous liver metastases of M5076 sarcoma; however, in combination with surgery or suboptimal doses of cisplatin, the compound exerted synergistic antimetastatic effects in the same model. These findings suggest that RP 56 142 could be used in cancer patients as an immunotherapeutic agent in combination with surgery, radiotherapy and/or conventional chemotherapy.

Biologically active casein peptides implicated in immunomodulation.

Maternal milk should not only be considered as a nutrient, but also as a protecting agent against aggressions from the neonate's new environment. Breast-feeding facilitates transmission of a passive immunity by multifunctional factors which have a direct effect on the neonate's resistance to bacterial and viral infections. Among these factors are the main milk proteins, the caseins: during enzymic digestion of human and bovine caseins, immunomodulating peptides are released. Corresponding synthetic peptides stimulated in vitro phagocytic activity of murine and of human macrophages and exerted in vivo a protective effect against Klebsiella pneumoniae infection of mice. These data suggest that casein peptides may exert a stimulating function on the immune system of the newborn.

Immunopotentiating activities of a low molecular weight lipopeptide, RP 56 142--studies in infectious models.

RP 56 142, N2-[N-(N-lauroyl-L-alanyl)-gamma-D glutamyl] L,L-2,6-diaminopimelamic acid belongs to a family of immunomodulating lipopeptides. Its structure is directly derived from that of lauroyltetrapeptide RP 40 639 which is a mixture of two stereoisomers, one of which (with D,D-2,6 diaminopimelamic acid) is totally devoid of in vivo activity. RP 56 142 displayed potent protective activities against bacterial infections such as K. pneumoniae, L. monocytogenes or S. typhimurium (at doses ranging between 0.03 and 100 mg/kg s.c., i.p., i.v.). In combined treatment protocols, suboptimal doses of RP 56 142 given preventively (day-1) or curatively (day 0 + 4h) significantly protected mice receiving antibiotics at doses which were ineffective when administered by themselves. Given s.c. 1 or 2 days before infectious challenge, RP 56 142 was able to normalize and even enhance significantly the resistance of mice previously immunocompromised by lomustine, 5-fluorouracile or hydrocortisone. These results correlated with the stimulation of the clearance of a virulent Salmonella typhimurium strain and with an important production of colony-stimulating factor in RP 56 142-treated mice.

[Beneficial effects of the combination of antibiotics and immunomodulating lipopeptides]. / Effects bénéfiques de l'association antibiotiques et lipopeptides immunomodulateurs.

Although antibiotics are efficient therapeutic weapons, their actions is limited in immunocompromised patients. The efficacy of immunomodulators which restore the immune system could be improved if they were associated to infra-active doses of antibiotics which prepare the bacteria to the immune system attack. Thus it seems possible to obtain a therapeutic gain with such an association and, consequently, to avoid the emergence of antibiotic-resistant germs.

Immunostimulating properties and three-dimensional structure of two tripeptides from human and cow caseins.

Some tripeptides obtained by enzymic digestion of caseins possess immunomodulating properties. In order to correlate activity and structure, X-ray analysis has been applied to two of them Leu-Leu-Tyr and Gly-Leu-Phe.

Immunostimulating hexapeptide from human casein: amino acid sequence, synthesis and biological properties.

A hexapeptide obtained from human casein by enzymatic digestion has been purified, sequenced and synthesized; its structure is: Val-Glu-Pro-Ile-Pro-Tyr. In vitro this hexapeptide stimulates the phagocytosis of opsonized sheep red blood cells by murine peritoneal macrophages. Administered intravenously to adult mice, it enhances the resistance to infection with Klebsiella pneumoniae.

Immunostimulating substances from human casein.

Delipidated human casein was digested with trypsin and the enzymatic digest was fractionated on Sephadex G-50. The peptidic fractions were assayed for immunomodulating activity in two in vitro models. Fractions corresponding to molecular weights in the range of 2,000 +/- 600 were found to possess stimulating activity in these models.

Comparative effects of an inflammatory reaction on the resistance of mice to bacterial and viral infections.

The induction in mice of a sterile subcutaneous granuloma exerted no influence upon the mortality following their infection with herpes type 1, murine hepatitis or encephalomyocarditis viruses. Attempts to reproduce the resistance -- which has been found to occur as a result of the granulomatous reaction, in the case of bacterial, fungal or protozoa infections and tumour invasions -- by varying the route and timing of the virus inoculation or the strain of mice have failed. We conclude that it is not merely through their inflammatory properties that some non-specific immunostimulating substances enhance resistance against viral infection.

[Immunostimulating and adjuvant activities of a low molecular weight lipopeptide]. / Propriétés immunostimulantes et adjuvantes d'un lipopeptide de faible poids moléculaire.

From crude extracts of a Streptomyces strain exhibiting immunopotentiating effects, a tetrapeptide was isolated and its structure established as L Ala leads to D isoGlu leads to L, L Dap comes from Gly. This peptide was devoid of biological activity but its chemical coupling with lauric acid gave a substance endowed with adjuvant and immunostimulating properties. This substance and the corresponding synthetic lauroyltetrapeptide were as active in this respect as the muramyl-dipeptide, thus far considered as the minimal adjuvant-active structure of bacterial cell walls: the presence of a sugar moiety is therefore not a prerequisite for immunopotentiating activities.

Carcinoma of the small intestine in regional enteritis: presentation of a case and review of the literature.

A case of carcinoma of the jejunum occurring in a patient with Crohn's disease of 30-years' duration is presented. Forty-seven previously reported small bowel carcinomas in Crohn's disease patients are reviewed. The incidence of small bowel carcinomas in patients with Crohn's disease has been cited as being as low as 0.08%, a figure which is still higher than the 1 in 10(9) population which would be predicted if the two diseases were independent of one another. The average age of incidence of the Crohn's carcinomas was 46.5 years while that for the de novo group was 55 years. The sexual ratios were 2.46:1 and 2:1, males to females, for the respective groups. The de novo carcinomas had a slight predilection for the duodenum at 40.7% while the latter group had a heavy predilection for the ileum at 70.8% and contained no duodenal carcinomas. The prognosis of the Crohn's group appeared to be much worse than that of the de novo group with five-year survivals of 3.7% and 20-22% respectively. Late diagnosis in the enteritis group was felt to be the major reason for this. Finally, several pathological differences between the lesions in both groups are presented.

Heterotypic protective immune reactions in mice infected with distinct serotypes of human influenza virus.

Infection of mice with subtype A0 OR A2 human influenza viruses, by a non-respiratory route causing no lethality, renders the animals markedly resistant to subsequent respiratory challenge with a strain differing from the first one through its haemagglutinin and neuraminidase antigens. This state of heterotypic immunity which appears rapidly (5 days) after the first infection, manifests itself during the second infection by a much reduced mortality, by less extensive lung lesions than in the control mice and by a final drop in lung virus titre (while in controls this titre stays at a high level until death) associated with a rapid rise of serum antibody levels against the haemagglutinin of the challenge virus and the "soluble" antigen common to type A strains. The development of this state of heterotypic immunity is dependent on the capacity of the first virus inoculated to replicate actively in the mouse. The role played by cell-mediated immunity in this phenomenon is evidenced by the fact that both the induction and the expression of this state of heterotypic resistance may be abolished by treatment of the mice with anti-thymocyte serum, while they are not affected by cyclophosphamide. Furthermore, in the mouse infected with an influenza A0 or A2 virus, it has been possible to demonstrate completely cross-reactive delayed type hypersensitivity reactions against the virions or their products. The fact that heterotypic immunity is not demonstrable between influenza viruses of type A and B favors the hypothesis that an antigen (matrix or nucleoprotein) common to all A subtypes--but different in B type strains--plays a role in these reactions of cross-protection.

Adjuvant and immunostimulating activities (in the absence of freund's incomplete adjuvant) of chemically modified low molecular weight mycobacterial peptidoglycans.

Relatively low molecular weight peptidoglycan fragments extracted from two strains of Mycobacterium tuberculosis var. hominis were chemically coupled with lauric acid. The fatty acid conjugates were compared with the native substances with respect to some immunopotentiating activities. In vitro, the mitogenic effect on murine spleen lymphocytes was significantly enhanced following conjugation. One of the lauric acid conjugates stimulated, upon intravenous administration in mice, the formation of antibody-producing cells in the spleen, while the native substance was devoid of such activity. In adjuvanticity tests performed in the guinea pig in the absence of mineral oil, the fatty acid conjugates generally exerted a higher adjuvant effect on antibody production or on delayed type hypersensitivity reactions than did the native preparations.

Adjuvant activities of chemically modified water-soluble substances from Mycobacterium tuberculosis.

Water-soluble peptidoglycan fragments extracted from the cells of two strains of Mycobacterium tuberculosis var. hominis were chemically conjugated with lauric or with palmitic acid. The coupling reaction was confirmed by physicochemical procedures. The native and the fatty acid-conjugated substances were studied for their adjuvant activity in the induction of delayed type hypersensitivity (DTH) reactions in guinea-pigs and on the production of circulating antibodies in the rabbit. Palmitic acid conjugation of one of the substances increased its adjuvanticity on DTH in the presence of mineral oil; lauric or palmitic acid conjugation rendered the substances adjuvant-active on DTH in the absence of mineral oil. Lauric acid, but not palmitic acid conjugation conferred on both substances an adjuvant activity on antibody production in the absence of mineral oil. Furthermore, lauric acid conjugation of one of the substances led to the appearance of an in vitro mitogen-like activity for murine spleen lymphocytes. In conclusion, fatty acid conjugation exerted a significant modifying effect on the immuno-potentiating activities of these peptidoglycan fragments, and such a chemical procedure may lead to the development of substances exerting a full adjuvant activity without the need of injecting them in an oily vehicle.

Increased resistance to virus infections of mice inoculated with BCG (Bacillus calmette-guérin).

CD-1 or OF-1 mice were inoculated intravenously with 1 mg per mouse (i.e. about 10(6) live bacilli) of Pasteur Institute BCG and challenged 15 to 31 days later with the following viruses introduced by various routes: encephalomyocarditis, murine hepatitis, type 1 and 2 herpes simplex, foot-and-mouth disease and A0 and A2 influenza viruses. In most cases, BCG-inoculated mice exhibited a significantly higher resistance to these lethal infections than control mice (overall survival in control: 18%; in BCG-inoculated mice: 41%). Enhancement of resistance by BCG was especially marked in infections with encephalomyocarditis, herpes simplex type 1 and influenza A2 viruses. Intercurrent infection of BCG-inoculated mice with non lethal doses of viruses did not abrogate their resistance towards subsequent challenge with lethal doses of an unrelated virus. The possible mechanisms of this enhancing effect of BCG on host's resistance are discussed in the light of the known effects of this immunostimulating agent on the various facets of the immune response and of the respective roles the latter play in the defence against virus infections.

Inhibitory effect of interferon on DNA and RNA synthesis in murine spleen cells stimulated by lectins.

Spleen cells from mice inoculated with partially purified preparations of interferon (Sp. Act. 1 X 10(7) i.u./mg protein, 0.2 ml i. v./mouse) were stimulated in vitro with phytohemagglutinin, concanavalin A or lipopolysaccharide. After 2 days of stimulation, the incorporation of 3H-thymidine into TCA-insoluble radioactivity was inhibited 50-90% when compared with cells from animals inoculated with mock interferon. Maximal inhibition, with optimal doses of lectins was obtained when interferon was;inoculated 18 hours before. This effect of interferon on DNA synthesis was preceeded by inhibition of the incorporation of 3H-uridine into TCA-insoluble material. When cells were pretreated in vitro with interferon for 24 hours and subsequently stimulated with PHA, RNA synthesis was inhibited by 30-40%, whatever was the dose of the mitogen. The synthesis of 4S tRNA, 18S and 28S ribosomal RNAs were inhibited to the same degree by interferon. The incorporation of methyl groups into cytoplasmic sRNA was unaltered.

In vivo antiviral activity of D-glucosamine.

Intraperitoneal treatments with D-glucosamine, an inhibitor of the glycosylation of the viral envelope, decreased the growth rate of tumors induced in quails or in chicks by Rous sarcoma virus and increased the survival of mice inoculated with human influenza virus.