sodium-dodecyl-sulfate and nickel-chloride

The human CD80 costimulatory molecule is an important signal between professional antigen-presenting cells and T helper cells. The immunobiology of CD80 expression by keratinocytes, especially during allergic and irritant contact dermatitis, however, is less well understood. CD80 cell surface expression and gene transcription by keratinocytes was increased when keratinocytes were exposed to certain allergens (chemicals that induce inflammation via hapten-specific T cells) and irritants (chemicals that are toxic to epidermal cells). Therefore, the human CD80 promoter was cloned and luciferase reporter constructs containing various promoter fragments were engineered. Promoter mapping of these CD80 constructs in transiently transfected keratinocytes showed that a construct containing the proximal 231 bp immediately upstream of the transcription start site of the CD80 promoter was most active in keratinocytes and was inducible to a level ranging from 2- to 10-fold higher in keratinocytes treated with certain allergens and irritants, compared with untreated keratinocytes. This pattern of promoter fragment activity in keratinocytes is identical to that found in professional antigen-presenting cells. This is the first demonstration that the CD80 promoter is active in keratinocytes and that this activity is further increased in keratinocytes treated with certain allergens and irritants. These data suggest that allergens and irritants may, in part, break peripheral tolerance by their direct effects on keratinocyte costimulatory molecule expression, thereby facilitating interactions with epidermotropic T helper cells via the CD80-CD28 or CTLA-4 pathways.

Topics: Allergens; Antigen-Presenting Cells; B7-1 Antigen; Chromosome Mapping; Dermatitis, Allergic Contact; Humans; Infant, Newborn; Interferon-gamma; Irritants; Keratinocytes; Male; Nickel; Promoter Regions, Genetic; Sodium Dodecyl Sulfate; Tetradecanoylphorbol Acetate; Transcription, Genetic; Up-Regulation

Irritant contact dermatitis is a major problem in dermatology. One important group of substances causing irritant dermatitis is detergents. Exposure of the skin to detergents is frequent in both work and domestic environments. In the present paper we have studied how the penetration through the skin, and thus the effect, of the detergent sodium lauryl sulfate (SLS) is altered when the temperature is raised from 22 degrees C to 40 degrees C or 60 degrees C. We found that the penetration of sodium lauryl sulfate increased with increasing temperature. When comparing the increased penetration of sodium lauryl sulfate with the change in NiCl penetration at the same temperatures, we found that the increase in penetration was more pronounced for the detergent. This implies that the detergent also had a different effect on the structure and function of the epidermal barrier itself. The results underline the importance of choosing the right (low) temperature when working with detergent solutions to reduce the risk of developing irritant contact reactions.

Topics: Dermatitis, Contact; Dermatitis, Irritant; Detergents; Humans; In Vitro Techniques; Nickel; Skin Absorption; Sodium Dodecyl Sulfate; Temperature

The effects of ouabain on muscle tension and the intracellular Ca2+ level ([Ca2+]i) were examined in guinea-pig aorta loaded with fura-2. Ouabain caused a gradual and sustained increase in both [Ca2+]i and muscle tension. There was a positive correlation between these two parameters. In Ca(2+)-free solution, ouabain did not affect either [Ca2+]i or muscle tension, suggesting that the ouabain-induced increase in [Ca2+]i was not due to Ca2+ release from storage sites. The ouabain-induced increase in [Ca2+]i and muscle tension was inhibited by Ni2+, which inhibits the Na+/Ca2+ exchanger, but not by verapamil. Furthermore, anionic and cationic amphiphiles were used as modulators of the Na+/Ca2+ exchanger. Sodium dodecyl sulfate accelerated the responses to ouabain, whereas dodecyltrimethylammonium bromide inhibited them. These results suggest that in the guinea-pig aorta, ouabain induces contraction by increasing the Ca2+ influx through the Na+/Ca2+ exchanger on the plasma membrane, but not through verapamil-sensitive Ca2+ channels.

Topics: Animals; Aorta; Calcium; Carrier Proteins; Cell Membrane; Electric Stimulation; Guinea Pigs; In Vitro Techniques; Male; Muscle Contraction; Muscle, Smooth, Vascular; Nickel; Ouabain; Quaternary Ammonium Compounds; Sodium Dodecyl Sulfate; Sodium-Calcium Exchanger; Verapamil