<p>Transition metals such as nickel (Ni), cobalt (Co), palladium (Pd), chromium (Cr) and gold (Au) are widely used as alloys in jewelry and biomaterials such as orthodontic and orthopaedic appliances. These metals also cause cell-mediated allergic contact dermatitis (ACD) reactions in a significant proportion of the population upon prolonged direct exposure. The immune mechanisms underlying the response to these metals are not yet well defined. In the studies described in this thesis we therefore investigated the profile of cytokine responses to various metal ions <i>in vitro</i> and the relationship with the ACD reaction <i>in vivo</i>. In the first study, we investigated the relationship between the profile and magnitude of Ni²⁺-induced cytokine responses <i>in vitro</i> and the degree of <i>in vivo</i> reactivity to Ni²⁺. PBMC from Ni²⁺-reactive (ACD) and non-reactive control subjects were cultured with or without NiCl₂. The numbers of IL-4-, IL-5- and IL-13-producing cells and the concentrations of IFN-γ, IL-10 and IL-13 produced were analysed by ELISpot and ELISA respectively. Ni²⁺ elicited a mixed Th1- and Th2-type cytokine profile in PBMC from ACD subjects with a positive correlation observed between the levels of the elicited cytokines and the degree of patch test reactivity. Hence, suggesting an involvement of both Th1- and Th2-type cytokines in ACD to Ni²⁺ and a direct association between the magnitude of the Ni²⁺-induced cytokine response overall and the <i>in vivo</i> reactivity to Ni²⁺. The impact of the regulatory cytokine IL-10 on Ni²⁺-induced Th1- and Th2-type cytokine responses in human PBMC was investigated in the next study. PBMC from blood donors with a history of Ni²⁺ reactivity and non-reactive control donors were stimulated with Ni²⁺ <i>ex vivo</i> with or without addition of human recombinant IL-10 (rIL-10) or neutralising mAb to IL-10. Depletion/enrichment experiments were performed to phenotype the Ni²⁺-specific cytokine producing cells. Exogenous rIL-10 significantly down-regulated the production of all cytokines but with a more pronounced effect on IFN-γ. IL-10 neutralisation, on the other hand, enhanced the levels of Ni²⁺-induced IFN-γ only. Ni²⁺-specific cytokine-producing cells in PBMC were found to be predominantly CD4⁺ T cells. Thus, IL-10 may play a regulatory role <i>in vivo</i> by counteracting the ACD reactions mediated by CD4⁺ T cells producing Th1-type cytokines. In the third study, we investigated the relationship between <i>in vivo</i> patch test reactivity to a number of metals (Ni, Co, Pd, Cr and Au) included in the standard and/or dental patch test series and <i>in vitro</i> responses to the metals in question. PBMC from metal patch test positive and negative control subjects were stimulated with a panel of eight metal salts and cytokine responses analysed by ELISpot and/or ELISA. A mixed Th1- (IL-2 and/or IFN-γ) and Th2-type (IL-4 and/or IL-13) cytokine profile was observed in PBMC from most metal allergic subjects upon <i>in vitro</i> stimulation with the metal(s) to which the subject was patch test positive. Our data suggest that other metals included in the standard and dental patch test series, just like Ni2⁺, induce a mixed Th1- and Th2-type cytokine profile in PBMC from ACD subjects <i>in vitro</i>. We further developed a simplified ELISpot protocol utilising plates precoated with capture monoclonal antibodies (mAb) and subsequent detection in one step using enzyme-labelled mAb, for enumerating the frequency of allergen (Ni²⁺)-specific cytokine producing cells. This was compared with a regular ELISpot protocol, with an overnight incubation for capture mAb adsorbtion and detection with biotinylated mAb followed by enzyme-labelled streptavidin. PBMC from Ni²⁺-reactive and non-reactive subjects were incubated with or without NiCl₂ and the enumeration of cells producing IFN-γ, IL-4 or IL-13 by the two protocols were compared. PBMC from Ni²⁺-reactive subjects showed significantly higher Ni²⁺-induced IL-4 and IL-13 responses and the number of antigen-specific cytokine-producing cells determined by the two ELISpot protocols correlated well. In a nutshell, our data point to the potential use of <i>in vitro</i> cytokine assays as diagnostic tools in distinguishing ACD subjects sensitised to different metals and non-sensitised subjects.</p>

Transition metals such as nickel (Ni), cobalt (Co), palladium (Pd), chromium (Cr) and gold (Au) are widely used as alloys in jewelry and biomaterials such as orthodontic and orthopaedic appliances. These metals also cause cell-mediated allergic contact dermatitis (ACD) reactions in a significant proportion of the population upon prolonged direct exposure. The immune mechanisms underlying the response to these metals are not yet well defined. In the studies described in this thesis we therefore investigated the profile of cytokine responses to various metal ions in vitro and the relationship with the ACD reaction in vivo. In the first study, we investigated the relationship between the profile and magnitude of Ni2+-induced cytokine responses in vitro and the degree of in vivo reactivity to Ni2+. PBMC from Ni2+-reactive (ACD) and non-reactive control subjects were cultured with or without NiCl2. The numbers of IL-4-, IL-5- and IL-13-producing cells and the concentrations of IFN-γ, IL-10 and IL-13 produced were analysed by ELISpot and ELISA respectively. Ni2+ elicited a mixed Th1- and Th2-type cytokine profile in PBMC from ACD subjects with a positive correlation observed between the levels of the elicited cytokines and the degree of patch test reactivity. Hence, suggesting an involvement of both Th1- and Th2-type cytokines in ACD to Ni2+ and a direct association between the magnitude of the Ni2+-induced cytokine response overall and the in vivo reactivity to Ni2+. The impact of the regulatory cytokine IL-10 on Ni2+-induced Th1- and Th2-type cytokine responses in human PBMC was investigated in the next study. PBMC from blood donors with a history of Ni2+ reactivity and non-reactive control donors were stimulated with Ni2+ ex vivo with or without addition of human recombinant IL-10 (rIL-10) or neutralising mAb to IL-10. Depletion/enrichment experiments were performed to phenotype the Ni2+-specific cytokine producing cells. Exogenous rIL-10 significantly down-regulated the production of all cytokines but with a more pronounced effect on IFN-γ. IL-10 neutralisation, on the other hand, enhanced the levels of Ni2+-induced IFN-γ only. Ni2+-specific cytokine-producing cells in PBMC were found to be predominantly CD4+ T cells. Thus, IL-10 may play a regulatory role in vivo by counteracting the ACD reactions mediated by CD4+ T cells producing Th1-type cytokines. In the third study, we investigated the relationship between in vivo patch test reactivity to a number of metals (Ni, Co, Pd, Cr and Au) included in the standard and/or dental patch test series and in vitro responses to the metals in question. PBMC from metal patch test positive and negative control subjects were stimulated with a panel of eight metal salts and cytokine responses analysed by ELISpot and/or ELISA. A mixed Th1- (IL-2 and/or IFN-γ) and Th2-type (IL-4 and/or IL-13) cytokine profile was observed in PBMC from most metal allergic subjects upon in vitro stimulation with the metal(s) to which the subject was patch test positive. Our data suggest that other metals included in the standard and dental patch test series, just like Ni2+, induce a mixed Th1- and Th2-type cytokine profile in PBMC from ACD subjects in vitro. We further developed a simplified ELISpot protocol utilising plates precoated with capture monoclonal antibodies (mAb) and subsequent detection in one step using enzyme-labelled mAb, for enumerating the frequency of allergen (Ni2+)-specific cytokine producing cells. This was compared with a regular ELISpot protocol, with an overnight incubation for capture mAb adsorbtion and detection with biotinylated mAb followed by enzyme-labelled streptavidin. PBMC from Ni2+-reactive and non-reactive subjects were incubated with or without NiCl2 and the enumeration of cells producing IFN-γ, IL-4 or IL-13 by the two protocols were compared. PBMC from Ni2+-reactive subjects showed significantly higher Ni2+-induced IL-4 and IL-13 responses and the number of antigen-specific cytokine-producing cells determined by the two ELISpot protocols correlated well. In a nutshell, our data point to the potential use of in vitro cytokine assays as diagnostic tools in distinguishing ACD subjects sensitised to different metals and non-sensitised subjects.

Exposure to a strong T-helper 2 (Th2)-like environment during fetal development may promote allergy development. Increased cord blood (CB) levels of the Th2-associated chemokine CCL22 were associated with allergy development during the first 2 y of life. The aim of the present study was to determine whether CB Th1- and Th2-associated chemokine levels are associated with allergy development during the first 6 y of life, allowing assessment of respiratory allergic symptoms usually developing in this period. The CB levels of cytokines, chemokines, and total IgE were determined in 56 children of 20 women with allergic symptoms and 36 women without allergic symptoms. Total IgE and allergen-specific IgE antibody levels were quantified at 6, 12, 24 mo, and 6 y of age. Increased CB CCL22 levels were associated with development of allergic sensitization and asthma and increased CCL17 levels with development of allergic symptoms, including asthma. Sensitized children with allergic symptoms showed higher CB CCL17 and CCL22 levels and higher ratios between these Th2-associated chemokines and the Th1-associated chemokine CXCL10 than nonsensitized children without allergic symptoms. A pronounced Th2 deviation at birth, reflected by increased CB CCL17 and CCL22 levels, and increased CCL22/CXCL10 and CCL17/CXCL10 ratios might promote allergy development later in life.

This master thesis considers an investigation of protective formulations (ointment, cream) containing enzyme inhibitors. Model experiments have been made on the enzyme trypsin. It is well accepted that feces and urine are an important causing factor for skin irritation (dermatitis) while using diaper. A protective formulation is a physical barrier that separates the harmful substances from the skin. It can also be an active barrier containing active substances, which can be active both towards the skin, and the substances from feces and urine. By preventing contact from these substances the skin will not be harmed, at least for a period of time. A number of different inhibitors were tested towards trypsin and they all showed good inhibition, two of the inhibitors were selected to be immobilized with the help of NHS-­activated Sepharose. Immobilization of these two inhibitors leads to a lesser extent of the risk of developing allergy and also that the possible toxic effect can be minimized.

Die Mastzellen der Haut sind bedeutende Immuneffektorzellen in der Pathogenese der Caninen Atopischen Dermatitis (CAD; OLIVRY et al. 1997). Diese Zellen schütten in der Sofort- und in der Spätphase der Überempfindlichkeitsreaktion des Typs I Entzündungsmediatoren aus. Diätetisch verabreichte Fettsäuren werden in zelluläre Membranen eingebaut und sind somit in der Lage, die Produktion und Freisetzung dieser Entzündungsmediatoren zu beeinflussen. In der Praxis konnte gezeigt werden, dass eine diätetische Ergänzung von n6- und n3-Fettsäuren im Verhältnis von 5 zu 1 eine Linderung der klinischen Symptomatik bei 40% der an CAD leidenden Hunde herbeiführte (SCOTT et al. 1997). Das Ziel der vorliegenden Arbeit war es, zu überprüfen, welche Auswirkungen der Einbau supplementierter n6- und n3-Fettsäuren auf die Fettsäurenzusammensetzung und die Prostaglandinfreisetzung caniner Mastocytomzellen (C2) hat und ob diese Zellen in Bezug auf ihren Fettsäurenstoffwechsel als Modell für die CAD geeignet sind. Die Kultivierung der Zellen erfolgte in einem Grundmedium (DEH) oder in mit 14 µM Linol- (C18:2n6, DEH-LA), Gammalinolen- (C18:3n6, DEH-GLA), Arachidon- (C20:4n6, DEH-AA), a-Linolen- (C18:3n3, DEH-LnA), Eicosapentaen- (C20:5n3, DEH-EPA) oder Docosahexaensäure (C22:6n3, DEH-DHA) angereichertem Medium. Das Wachstum der C2 wurde in allen Kulturmedien über 11 Tage kontrolliert. Für die weiteren Untersuchungen wurden die Zellen am 4. bzw. 8. Tag geerntet, zweimal mit phosphatgepufferter Kochsalzlösung gewaschen und anschließend unter Stickstoff getrocknet. Die Ermittlung der Fettsäurenzusammensetzung der C2 erfolgte mittels Gaschromatographie nach Extraktion und Umesterung der Phospholipide. Dabei wurde L-a-Phosphatidylcholin-C17:0 als Interner Standard genutzt. Für die Bestimmung der Prostaglandine (PG) D2 und E2 wurden die Zellen mit dem Wespengift Mastoparan stimuliert. PGD2 wurde mittels eines PGD2-Methoxim-Enzym-Immunoassay (EIA) und PGE2 wurde mit Hilfe eines Radio-Immunassays (RIA) bestimmt. Die C2 zeigten in allen Kulturmedien eine Vermehrung lebender Zellen bis zum 8. Kultivierungstag, danach nahm die Zahl der abgestorbenen Zellen deutlich zu. Die Fettsäurensupplementierung beeinflusste das Zellwachstum nicht. Die erhöhte Zufuhr der Fettsäuren bewirkte eine Konzentrationserhöhung der entsprechenden Fettsäuren in den C2 (LA 4,9-fach, GLA 6,9-fach, AA 6-fach, LnA 9,3-fach, EPA 6,5-fach, DHA 8,4-fach). Weiterhin wurden signifikante Erhöhungen von Fettsäurenmetaboliten, die über die Elongasen und die D6-Desaturase aus den zugegebenen Fettsäuren gebildet werden, in den C2 gefunden. Produkte der D5-Desaturase waren dagegen nur in geringen Mengen nachweisbar. Ein zeitabhängiger Effekt des Einbaus der geprüften supplementierten Fettsäuren konnte nur für LA festgestellt werden, welche nach 8 Tagen in DEH-LA kultivierten C2 signifikant stärker eingebaut wurde als nach 4 Tagen. Die vorliegenden Ergebnisse lassen die Schlussfolgerung zu, dass in den C2 eine geringe Aktivität der D5-Desaturase vorliegt. Da eine niedrige Aktivität dieser Desaturase als möglicher Pathogenesemechanismus für das Auftreten der CAD verantwortlich gemacht wird, erscheinen die C2 als Modell für weitere Untersuchungen der CAD geeignet. Die durch Mastoparan stimulierte Freisetzung von PGE2 der C2 war bei der Kultivierung der Zellen im DEH-LnA und DEH-DHA signifikant erniedrigt und im DEH-AA und DEH-EPA signifikant erhöht. Die Ursache für die unterschiedlichen PGE2-Konzentrationen in C2 nach dem Zusatz der verschiedenen n3-Fettsäuren (LnA, EPA, DHA) ist bisher unklar. Verschiedene Möglichkeiten der Beeinflussung des Prostaglandinstoffwechsels durch diese Fettsäuren werden diskutiert. Auf Grund der erhaltenen Ergebnisse können die C2 als Modell genutzt werden, um die Mechanismen der Produktion von Prostaglandinen oder anderen Entzündungsmediatoren näher zu untersuchen und somit zur Erforschung der Pathogenesemechanismen der atopischen Dermatitis des Hundes sowie des Menschen beizutragen. / Cutaneous mast cells are considered as key immune effector cells in the pathogenesis of canine atopic dermatitis (CAD; OLIVRY et al. 1997). These cells release immediate-phase and late-phase mediators of inflammation. Dietary fatty acids are incorporated in cellular membranes and seem to influence mediator production and release. A dietary intervention with n6- and n3-fatty acids with a ratio from 5 to 1 alleviated clinical symptoms in 40% of atopic dogs (SCOTT et al. 1997). The purpose of this study was to examine the effects of n6- and n3-fatty acids on the fatty acid composition and the production of prostaglandins in canine mastocytoma cells (C2) as a possible model for CAD. Cells were cultured in a basic medium (DEH) or with additional 14 µM linoleic (C18:2n6, DEH-LA), gammalinolenic (C18:3n6, DEH-GLA), arachidonic (C20:4n6, DEH-AA), a-linolenic (C18:3n3, DEH-LnA), eicosapentaenoic (C20:5n3) or docosahexaenoic acid (C22:6n3, DEH-DHA). Cell growth was examined for 11 days in all media. The cells were harvested after 4 or 8 days, washed twice with phosphated buffered saline and dried under nitrogen for fatty acid analysis. The fatty acid composition was determined by gas chromatography after extraction and transesterification of the phospholipids using di-C17-phosphatidylcholin as internal standard. For measurment of prostaglandin (PG) D2 and E2 the C2 were stimulated with the wasp venom peptide mastoparan. PGD2 was measured by PGD2-methoxim-enzymimmunoassay (EIA) and PGE2 was determined by radioimmunoassay (RIA). Cell growth increased from day 1 to 8 and decreased thereafter in all media conditions. The supplied fatty acid did not influence the cell growth. Added fatty acids increased the concentration of these fatty acids in C2 (LA 4.9-fold, GLA 6.9-fold, AA 6-fold, LnA 9.3-fold, EPA 6.5-fold, DHA 8.4-fold). Futhermore elongated and D6-desaturated products of the corresponding fatty acids were significantly elevated, however D5-desaturated products were not measurable. An increased time dependent incorporation was only detectable for LA after culturing C2 in DEH-LA. The results let us assume that C2 has no activity of the D5-desaturase. If the assumed low activity of these desaturase is one of the mechanisms underlying the pathogenesis of CAD, C2 seems to be an adequate model for CAD. The production of PGE2 after stimulation with mastoparan was significantly reduced when C2 were cultured in DEH-LnA and DEH-DHA and was significantly increased when C2 were cultured in DEH-AA and DEH-EPA. The reason for the different PGE2-production in C2 after the treatment with the n3-fatty acids (LnA, EPA or DHA) being unsettled. The observed results suggest, that C2 could be used to investigate the mechanisms of production and release of prostaglandins or other mediators as a model to improve our understanding of the pathogenesis of canine or human atopic dermatitis.

Bronopol has been used as a preservative in drugs and cosmetics since 1964. Bronopol has low dermal irritancy at levels commonly used in cosmetics and pharmaceuticals but it is significantly irritating at higher concentrations. Laboratory testing of bronopol indicates a low potential for dermal sensitization; however, a number of case reports demonstrate human allergenic reactions. No reports were identified on the allergenic properties of bronopol for the inhalation route of exposure. In 1983 approximately 5,200 people in the United States were occupationally exposed to bronopol. Current novel uses of bronopol include mold remediation and the sanitizing of ventilation system components. These new applications have the potential to expose vast new populations to the chemical. Since 89 million people in the United States work in indoor environments and 50 million Americans suffer from allergies, it is likely that a sizeable portion of these populations will be exposed to bronopol. This is significant since the dermal sensitizing properties of bronopol suggest that the material may also be a respiratory sensitizer, potentially resulting in chemically induced asthma. More people are being diagnosed with asthma today than at any time in the past; the causes of this increased prevalence are largely unknown. In this work an existing ultraviolet spectrophotometric method for analysis of bronopol has been combined with conventional industrial hygiene air sampling techniques. No combined air sampling and analytical method for bronopol has previously been published in the literature. A calibration curve has been developed with a linear range of 1 ug/ml to 25 ug/ml. The instrumental limit of detection is 1 ug/ml with an instrumental limit of quantitation of ca. 3 ug/ml. During chamber sampling trials analytical recovery for treated glass fiber filters yielded a sampling recovery efficiency averaging 99.9 %. Bronopol concentration obtained during chamber sampling trials ranged from 10.80 mg/m3 to 21.59 mg/m3, with a pooled coefficient of variation of 4.33 % for all chamber sampling sets. Treated glass fiber filters spiked with bronopol were found to be stable for a period of 48 hours; derivatized bronopol solutions were found to be stable for a period of fourteen days.

Šio tyrimo tikslas buvo įvertinti Malassezia pachydermatis paplitimą sveikų ir kliniškai dermatitu sergančių šunų tarpe. Tyrimo metodika. Tyrimas atliktas su 118 šunimis. 33 šunys buvo kliniškai sveiki, o 85 – turėjo dermatitus įvairiose kūno vietose. Šunims buvo atliekamas odos citologinis tyrimas. Mėginys tyrimui buvo imamas objektinį stiklelį priglaudus prie odos ir gautą mėginį nudažius Diff-Quik® (Dade AG, Dudingen, Switzerland) dažais. Tyrimo metu buvo ieškoma M. pachydermatis mielių. Mėginiai kliniškai sveikiems šunims buvo imami nuo kaklo, alkūnių, kirkšnių, tarpupirščių ir iš ausų. Sergantiems dermatitu mėginiai buvo paimti iš ausų, alkūnių, kaklo, kirkšnių, kojų, krūtinės, nugaros, pilvo, snukio. Tyrimo rezultatai ir išvados. Nustatėme, kad kliniškai dermatitu sergančiųjų tarpe M. pachydermatis paplitimas buvo didesnis 59% (p<0,05), negu kliniškai sveikų šunų tarpe. M. pachydermatis mielės sergančių šunų grupėje daugiausia buvo paplitusios ausyse (p<0,05). Tokie veiksniai kaip šunų lytis, veislė, amžiaus grupė, plauko ilgis, ausų kaušelio tipas M. pachydermatis paplitimo neįtakojo (p<0,05). Lauke laikomų šunų tarpe M. pachydermatis paplitimas buvo 21 % didesnis (p<0,05), negu tarp patalpose laikomų šunų. O tarp dažnai maudomų šunų M. pachydermatis pasireiškia 2,5 karto dažniau, nei tarp retai maudomų (p<0,05). Išsiaiškinome, kad konkurentinės ligos ir gydymas gliukokortikoidais įtakoja M. pachydermatis mielių sukeltą dermatitą. Šunys, sergantys konkurentinėmis... [toliau žr. visą tekstą] / The objective of the study was to assess the prevalence of Malassezia pachydermatis in clinically healthy and ill dogs that were suffering from dermatitis Research methodology. The test was performed with 118 dogs. 33 dogs were clinically healthy but 85 had dermatitis in various body areas. The dogs were examined by performing skin cytological examination. The sample for examination was taken by touching glass slide on the skin and staining the resulting sample with Diff-Quik® (Dade AG, Dudingen, Switzerland) paint. During the investigation was sought to find M. pachydermatis yeast. The samples of clinically healthy dogs were taken from the neck, elbows, groin, toes and ears. Dogs that were suffering from dermatitis, samples were taken from the ears, elbows, neck, groin, legs, chest, back, abdomen and foot. The research results and conclusions. We determined that among patients that were clinically ill with dermatitis M. pachydermatis prevalence was higher by 59 % (p<0.05) than among clinically healthy dogs. The group of dogs with M. pachydermatis was mostly prevalent in the ears (p<0.05). Factors such as gender, breed, length of hair, earlobes and age group type of dogs did not affect the incidence of M. pachydermatis (p<0.05). Among dogs that were held outdoor the prevalence of M. pachydermatis was 21 % higher (p<0.05) than for dogs in the premises. For dogs that were often bathed M. pachydermatis occurs 2.5 times more often than rarely bathed (p<0.05). We found out that... [to full text]

Darbe aprašoma blusų sandara, jų vystymas ir paplitimas, taip pat labiausiai paplitusių alerginių dermatitų patogenezė bei simptomai. Atlikto tyrimo rezultatai, kad būtų aiškiau, pateikiami diagramomis su trumpu jų aprašymu, jie apibendrinami ir padaromos išvados. / Thesis describes the structure of the fleas, their development and distribution, as well as the most common allergic dermatitis pathogenesis and symptoms. The research results are clearly presented charts with a short description of it, they are summarized and lead to conclusions.

A prospective study was performed to evaluate a biological medication in the treatment of digital dermatitis (DD) in dairy cattle. The study was divided into four parts; i) on farm evaluation of DD and treatment effects and comparison between the biological ointment and OTC-spray, ii) statistical evaluation, iii) histological examination using FISH and iv) microbiological examination and culture if bacteria found in biopsies from infected skin.

Seit Mitte der 1980er Jahre werden diätetische Ergänzungen von Futtermitteln mit mehrfach-ungesättigten Fettsäuren (PUFA) als nebenwirkungsfreie Therapeutika zur Behandlung atopischer Erkrankungen eingesetzt. Verschiedene Studien konnten dabei insbesondere bei einem n6:n3-Fettsäurenverhältnis von 5 bis 10:1 eine Linderung klinischer Symptome bei an Caniner Atopischer Dermatitis (CAD) leidenden Hunden feststellen. Die zugesetzten Fettsäuren beeinflussen auf molekularer Ebene unter anderem die zelluläre Fettsäurenzusammensetzung, Membraneigenschaften, Lipidmediatoren, intrazelluläre Signaltransduktionswege, Enzymaktivitäten sowie die Genexpression. Den in der Literatur beschriebenen positiven Effekten von PUFA steht die Feststellung gegenüber, dass insbesondere diese Fettsäuren einem radikalischen Angriff unterliegen und begünstigend auf die Entstehung von Lipidperoxiden sowie deren Abbauprodukten wirken. In diesem Zusammenhang konnte in verschiedenen Untersuchungen festgestellt werden, dass eine hohe Konzentration reaktiver Sauerstoffspezies und Lipidperoxide bzw. deren Abbauprodukte zu einer Schädigung der DNA führen. Eine zentrale Rolle in der Pathogenese der CAD nehmen die Mastzellen der Haut ein. Bei Einwirkung eines Allergens schütten sie einerseits präformierte Entzündungsmediatoren aus und produzieren auf der anderen Seite auch neue Mediatoren. Ziel der vorliegenden Arbeit war es, die Auswirkungen einer Supplementierung des Zellkulturmediums einer caninen Mastozytomzelllinie (C2) mit unterschiedlichen n6- und n3-FS, unter Berücksichtigung des Einflusses auf das Fettsäurenmuster und das Wachstum, auf oxidative Parameter der Zellen zu untersuchen. Die Kultivierung der C2 erfolgte zur Kontrolle im Grundmedium und daneben in Linol- (C18:2n6), Linolen- (C18:3n3), Arachidon- (C20:4n6) und in Eisosapentaen- (C20:5n3) säure-supplementiertem Medium (je 20 μM). Das Wachstum der C2 wurde über die Dauer von 8 Tagen verfolgt. Am 8. Tag der Kultivierung wurden die Zellen für folgende Bestimmungen gewonnen  Gehalt an α-Tocopherol in den Zellen und im Medium mit HPLC  Fettsäurenmusters mittels Gaschromatographie  intrazelluläre reaktive Sauerstoffspezies mittels Fluoreszenzfarbstoff  Lipidperoxidabbauprodukte mittels Thiobarbiturat-Reaktive Substanzen-Test  oxidative DNA-Schäden mittels Comet-Assay Die Ergebnisse zeigen, dass das Wachstum der C2 durch die Supplementierung des Mediums mit n3- und n6-FS nicht beeinflusst wird. Die supplementierten FS sowie ihre Desaturierungs- und Elongationsprodukte reichern sich in den zellulären Membranen an. Die Produkte der Δ5-Desaturase sind jedoch nicht oder nur geringfügig erhöht, was für das Vorliegen eines Desaturasedefektes spricht. Die mit PUFA kultivierten C2 weisen eine erhöhte intrazelluläre ROS-Konzentration, sowohl mit als auch ohne Zufuhr eines Stressors auf. Dabei zeigt sich eine Abhängigkeit von der Anzahl der Doppelbindungen der zellulären FS. Auch eine erhöhte Menge an Lipidperoxidabbauprodukten ist mit steigender Anzahl von Doppelbindungen der FS festzustellen. Diese Ergebnisse spiegeln sich in einem erhöhten Kernschädigungs-Score bei den mit PUFA supplementierten C2 wieder. Die Ergebnisse der vorliegenden Arbeit zeigen, dass PUFA eine pro-oxidative Wirkung auf C2-Zellen haben. Frühere Studien konnten zeigen, dass eine Zunahme der oxidativen Anfälligkeit von Zellen durch eine gezielte Zufuhr von Antioxidantien teilweise kompensierbar ist. Diese Feststellungen legen die Schlussfolgerung nahe, eine kombinierte Verabreichung von PUFA und Antioxidantien vorzunehmen, um die negativen Effekte diätetisch verabreichter FS zu kompensieren. Inwiefern eine solche Kombination mit antioxidativen Substanzen diese pro-oxidativen Effekte beeinflussen kann, sollte in weiteren in vitro Studien und schließlich Fütterungsstudien (in vivo) untersucht werden.