The association between trafficrelated air pollution and respiratory symptoms was studied using a longitudinal observational design with repeated measures in 82 children attending elementary schools in Utrecht (urban) or Bilthoven (suburban). Selection of the schools was based on yearly mean values for black smoke (BS), indicative for trafficrelated air pollution: Utrecht 53 plusminusg/m3 and Bilthoven 18 plusminusg/m3. Levels of the air pollutants, NO, NO2, CO and BS, as indicators of traffic related air pollution, were consistently higher in Utrecht than in Bilthoven (mean daily ratios 8, 1.5, 1.8 and 2.7, respectively). Children living in Utrecht (moderate exposure) showed higher mean levels (p<0.05): IL-8 (32%), urea (39%), uric acid (26%), albumin (15%), and the NO metabolites nitrate & nitrite (21%) in nasal lavage, compared to children living in Bilthoven (low exposure). Associations were demonstrated between PEF, NO in exhaled air and inflammatory parameters in nasal lavage and ambient levels of PM10, BS, NO2 and NO. Highly exposed children living in Utrecht showed per unit increase in air pollution levels increased responses in PEF, exhaled NO and nasal release of uric acid, urea, nitrite and nitrate as compared to children living in a suburban environment (Bilthoven). The conclusion is that children regularly exposed to moderate levels of trafficrelated air pollution show increased mean nasal levels of inflammatory biomarkers, and respond more pronounced to the same increments in air pollution than children living in a suburban environment and exposed to low background levels of air pollution.

De stand van zaken betreffende de ontwikkeling van immuunfunctie testen voor de bot, Platichthys flesus is beschreven. Epidemiologische veldstudies hebben aangetoond dat deze platvis species een hoge prevalentie aan infectieuze ziekten heeft, hetgeen gecorreleerd kan worden met de aanwezigheid van contaminanten in het aquatische milieu. Om een mogelijk causaal verband vast te kunnen stellen en om de bot als indicator species te kunnen gebruiken, zijn immuunfunctie-testen ontwikkeld. Het rapport beschrijft de ontwikkeling en toepassing van assays voor het bepalen van niet-specifieke cytotoxie, lymfocytenstimulatie en de immunohistochemische identificatie van leukocyt populaties in de bot. Deze assays, tezamen met andere testen die momenteel in ontwikkeling zijn, zullen gebruikt worden om de immuunstatus van de bot te 'peilen' in immunotoxicologische experimenten.

In recent years, mass mortalities among seals and dolphins have been attributed to infections with different morbilliviruses. In all cases, these marine top predators were exposed to high levels of persistent lipophilic environmental contaminants accumulated through the food chain. This observation led to the hypothesis that a contaminant-related suppression of the immune system might have contributed to the severity of the virus outbreaks. We conducted a semi-field feeding experiment, in which we fed two groups of harbour seals (Phoca vitulina) fish with different levels of contaminants. During a period of 2 1/2 years, blood samples were taken at regular intervals, and the functioning of different compartments of the immune system was monitored and compared. We found impaired natural killer (NK) and specific T cell responses in the seals fed contaminated fish. This is the first demonstration of immunosuppression in mammals following chronic exposure to environmental contaminants at ambient environmental levels.

Mass mortalities among seals and dolphins inhabiting contaminated marine regions have led to speculation about a possible involvement of immunosuppression associated with environmental pollution. To evaluate whether contaminants at ambient environmental levels can affect immune function of seals, we carried out an immunotoxicological study under semifield conditions. Two groups of 11 harbour seals (Phoca vitulina) originating from a relatively uncontaminated area were fed herring from either the highly polluted Baltic Sea or the relatively uncontaminated Atlantic Ocean. Changes in immune function were monitored over a 2 1/2-year period. The seals that were fed contaminated Baltic herring developed significantly higher body burdens of potentially immunotoxic organochlorines and displayed impaired immune responses as demonstrated by suppression of natural killer cell activity and specific T-cell responses. During a 2-week fasting experiment performed at the end of the feeding study, mobilization of organochlorines from the blubber did not lead to a strong increase of contaminant levels in the blood, and no enhancement of the existing immunosuppression was observed. These results demonstrate that chronic exposure to environmental contaminants accumulated through the food chain affects immune function in harbour seals, whereas short-term fasting periods, which are normal for seals, do not seem to pose an additional risk. The seals of this study were not exposed perinatally to high levels of environmental chemicals, and body burdens of organochlorines measured near the end of the study were lower than those generally observed in free-ranging seals inhabiting many contaminated regions. Therefore, it may be expected that environmental contaminants adversely affect immune function of free-ranging seals inhabiting contaminated regions at least as seriously as observed in these studies.

Disease outbreaks with high mortality rates among seals and dolphins have recently attracted considerable public and scientific interest. Although in most cases morbillivirus infections were shown to be the primary cause of the disease outbreaks, it was speculated that pollution-induced immunosuppression had played a contributory role. Here we present results of a prospective study under semifield conditions, in which two groups of harbor seals (Phoca vitulina) were fed herring from marine regions with different contamination levels; the highly polluted Baltic Sea and the relatively unpolluted Atlantic Ocean. During a period of 93 weeks, parameters related to immune function were monitored and compared between the two groups. We found that natural killer-cell activity and mitogen-induced proliferative T-cell responses from the seals feeding on herring from the Baltic Sea were significantly lower. In addition, we observed higher levels of circulating polymorphonuclear granulocytes in these animals, which may indicate an increase in the occurrence of bacterial infections. This is the first demonstration of impaired immunological functions in mammals associated with chronic exposure to environmental contaminants accumulated through the marine food chain.

In this experiment 20 one year old bulls received a single intramuscular injection of the anabolic preparation diethylstilbestrol dipropionate (DES-DP) (an oil preparation or an emulsion). Four animals received a corresponding placebo. The application of DES-DP to bulls caused characteristic histological alterations in the peripheral glandular epithelium of the prostate, which could be observed until four weeks after treatment. The value of histological investigation as a screening method was, however, limited by the occurrence of only few metaplastic lesions and a rapid recovery. By contrast, immunohistochemistry using a polyclonal cytokeratin antiserum K40 appeared to be a specific and very sensitive method to detect oestrogen-induced lesions in the prostate. In only two animals, six weeks after injection with the DES-emulsion, false-negative results were obtained, demonstrating the potential value of this screening method. The excretion of DES in the urine and faeces was monitored using radioimmunoassay following chromatographic purification of the urine and faeces extracts. The excretion of DES in urine was faster for animals of the oil group. The DES content in urine decreased to the 1 microgram/l level after 42 days (emulsion group) or 70 days (oil group). The excretion in faeces was comparable to that in urine. After day 21 the excretion patterns of the two excreta were indistinguishable.

This report describes procedures to quantify IgA responses in the rat sensitized to ovalbumin or infected with the parasite Trichinella spiralis: an ELISPOT detecting specific IgA antibody producing cells in lymph nodes, and an ELISA demonstrating IgA antibody in scrum and gut mucosal scrapings. For this purpose a mouse monoclonal anti‐rat IgA antibody was produced. This IgG1‐κ1 antibody recognized rat IgA but not rat IgM, IgG, or IgE. It proved very suitable in both assays. Using this reagent we could demonstrate large numbers of IgA anti‐ovalbumin‐producing cells in the mesenteric lymph nodes is 15.days after sensitization to ovalbumin via the Peyer's patches. At 28 days after sensitization the numbers were much lower. IgA antibody titres to ovalbumin in serum were maximal between days 14 and 21 after immunization. Maximal numbers of IgA anti‐T. spiralis‐producing cells were found in the mesenteric lymph nodes 12 days after infection with muscle larvae, followed by a sharp decrease at 15 days. Maximal IgA anti‐T spiralis antibody titres in serum and mucus scrapings of small intestines were found on days 10 and 12 after oral infection with the parasite