Search

Coal tar-treated psoriasis patients were used as a model population to test a newly developed enzyme-linked immunosorbent assay (ELISA) for urinary excretion of benzo(a)pyrene and related polycyclic aromatic hydrocarbons (PAHs). The ability of the ELISA to detect exposure was also compared with that of two previously established biomonitoring methods, measurement of urinary 1-hydroxypyrene by high performance liquid chromatography with fluorescence detection and mutagenicity measured by the Salmonella typhimurium mutagenesis assay. Urine samples were collected from 57 patients and 53 untreated volunteers. Urinary excretion of PAH metabolites, measured by competitive ELISA with a monoclonal antibody (4D5), was elevated in patients (mean, 730 +/- 1370 mumol/mol creatinine) compared with untreated volunteers (110 +/- 90 mumol/mol creatinine; P < 0.0001). 1-Hydroxypyrene also was elevated in patients (mean, 547 +/- 928 mumol/mol creatinine) compared with volunteers (mean, 0.14 +/- 0.17 mumol/mol creatinine; P < 0.0001). Much larger differences between mean values in patients and volunteers were observed with the 1-hydroxypyrene assay compared with the PAH metabolite ELISA. No significant effect of smoking could be detected by either assay. Analysis by the Salmonella typhimurium mutagenesis assay indicated elevated mutagenicity in urine from patients (1410 +/- 2750 revertants/mmol creatinine) compared with volunteers (715 +/- 846 revertants/mmol creatinine; P = 0.072). In all subjects, there was a good correlation between the PAH metabolites and both 1-hydroxypyrene (r = 0.717; P < 0.0001) and urinary mutagenicity (r = 0.317; P = 0.004). These results suggest that the ELISA, which easily can be carried out on large numbers of samples, can be used for monitoring urinary excretion of PAHs in a high exposure population. Ongoing studies are designed to determine its applicability to lower exposure populations.

Ultraviolet light in solar radiation is responsible for more than 600,000 malignancies each year in the United States alone, making it the most efficient environmental carcinogen known. Ultraviolet radiation-induced direct DNA damage is thought to be responsible for its initiating properties, while the promotional aspects of such radiation are poorly defined and only recently gaining attention. We show here for the first time that physiologically relevant doses of ultraviolet radiation induce phosphorylation of the epidermal growth factor receptor in A431 keratinocytes at tyrosine sites within 30 min. Such alteration of this major signal transduction system is probably an important step in the ultraviolet radiation-induced, epidermal cell-signalling cascade.

Monoclonal antibodies specific for DNA damaged by 8-methoxypsoralen (8-MOP) plus ultraviolet A (UVA) light were used to study adduct formation in human keratinocytes and mouse and rat skin in vivo. This antibody does not cross-react with nonmodified DNA or free 8-MOP. Sensitive competitive enzyme-linked immunosorbent assays with color or fluorescence endpoints were used to quantitate adducts on DNA isolated from treated keratinocytes or skin samples. Localization of 8-MOP-DNA adducts was studied by indirect immunofluorescence with fluorescein-conjugated anti-mouse-IgG antibodies. When cultured keratinocytes were treated with 8-MOP and UVA, immunofluorescence was localized in the nucleus. There was no fluorescence in untreated control cells or treated cells incubated with nonspecific serum. Comparison of intensity of immunofluorescence staining with quantitation of adduct levels by enzyme-linked immunosorbent assay indicated that the limit of sensitivity of the immunofluorescence technique is 9.0 fmol adduct/micrograms DNA or 2.9 adducts/10(6) nucleotides.