Quercetin prevents UV-induced local immunosuppression, but does not affect UV-induced tumor growth in SKH-1 hairless mice.

Ultraviolet is thought to induce skin tumors by its dual activity as a mutagenic agent and a suppressor of cell-mediated immunity. In the present study the effects of quercetin, a flavonoid-containing compound, on carcinogenesis and immunosuppression were studied in SKH hairless mice exposed to suberythemal doses of UV for up to 17 weeks. It was found that quercetin did not affect the onset or growth of non-melanoma skin tumors resulting from UV exposure. In contrast, it prevented the suppression in contact hypersensitivity (CHS) to picryl chloride induced by UV. The mechanism of this prevention might be explained by the observation that the decreased number of epidermal Langerhans' cells is partly prevented by the quercetin. Quercetin did not alter the effects of UV in increasing numbers of spleen and lymph node cells, only partly in decreasing the CD8-positive cells in spleen cell populations and decreasing the lymphoproliferative response of spleen cells to the mitogens concanavalin A and phytohemagglutinin. Thus oral quercetin did not prevent UV-induced carcinogenesis although it restored the skin-associated CHS response probably by protecting the antigen-presenting cells in the skin.

Nasal lavage as tool for health effect assessment of photochemical air pollution.

It is widely accepted that humans exposed to known concentrations of ozone under controlled conditions exhibit reversible changes that affect the large and small airways as well as the alveolar region of the lung. Among the reversible changes, the induction of inflammatory responses in the lung are of major concern. Many of the cell types found in the lining of the nasopharyngeal region are similar to cells of the tracheal and bronchial lining. therefore, it has been suggested that the cellular responses in the nose to toxicants are likely to be similar to the lower airway at the same dose of the agent. If these pollutants are respiratory irritants, capable of causing cellular damage, effects may therefore be detected in the nasal passage. Experimental studies have shown that the inflammatory response in the nose may be predictive for the situation in the lung. In this paper we described the results of a feasibility study on the use of nasal lavage for epidemiological studies. Nasal lavages were performed in 12 volunteers, 5-7 times per volunteer during 2 months. Polymorph nuclear leukocytes (PMN's), immune mediators and markers for exudation were monitored in the nasal lavage (NAL). It was found that the procedure of the nasal lavage technique was minimally invasive, very well tolerated and no adverse side effect were observed. The leukocytes, the proteins myeloperoxidase (MPO), eosinophil cationic proteins myeloperoxidase (MPO), eosinophil cationic protein (ECP) and interleukin-8 (IL-8) were detectable in NAL of most volunteers, while tryptase IgE and IL-6 were not detectable. Exudation markers albumin, urea and uric acid were also detectable. The coefficient of variance (CV) values of the various cells and mediators varied between 13% and 137%. It was calculated that, except for the number of leukocytes and the concentration of ECP, it should be possible to detect ozone effects with a study-protocol of 6 repeated measurements among 35 children and an assumed 26% increase in cells or mediators per 100 micrograms O3 per m3. To measure increase in leukocytes number or in ECP concentration more children are needed. In conclusion, this pilot study has shown that it is possible to measure relevant biomarkers in NAL, and that these assays can be easily incorporated in epidemiological studies.