Nickel sulphate and epoxy resin: differences in iron status and glutathione redox ratio at the time of patch testing

The reactive patch test reaction is a useful model to characterize oxidative stress in acute allergic contact dermatitis. This model was used to study oxidative stress in the skin of individuals allergic to nickel and epoxy resin. The study included six and five patients, respectively, whose skin was simultaneously biopsied from a positive patch test site and from an apparently healthy area. The biopsies were homogenized and used for determination of iron content, unbound iron binding capacity, diene conjugate levels, and glutathione redox ratio. A positive test reaction to 5% nickel sulphate was accompanied by 2.5-fold increase in iron level as compared to apparently healthy skin (P<0.1). The percentage saturation of iron-binding capacity and the glutathione redox ratio were significantly increased (P<0.01 and P<0.05, respectively). Reactive patch test responses to 1% epoxy resin were not accompanied by clear alterations in iron status or glutathione redox ratio. Our investigation showed that apart from oxidative burst caused by accumulation of inflammatory cells, hapten properties might also influence the oxidative stress status of the skin. The high incidence of nickel allergy may be attributed, at least in part, to the influence of nickel ions on the glutathione redox ratio and iron status of the skin.     

Characterization of a U-937 subline which can be induced to differentiate in serum-free medium.

We report the selection and characterization of a U-937 subline which is capable of long-term growth in serum-free medium and can be induced to differentiate. The subline (U-937-1SF) can be maintained in standard RPMI-1640 medium supplemented by antibiotics only. As compared to the serum-dependent U-937 parental cell line, U-937-1SF produced lower amounts of lysozyme and elastase and had a decreased surface expression of complement receptor 1 (CD35) and myeloid antigens CDw17 and CD38. Apart from these alterations, the U-937-1SF cells appear to be morphologically, cytogenetically and phenotypically similar to the parental U-937 clone-1 cells. The capacity of U-937 clone-1 cells to undergo phorbol myristic acid (PMA)-, vitamin D3 (VitD3)- and retinoic-acid (RA)-induced differentiation was retained in the U-937-1SF cells as evidenced by the induced growth arrest, development of a monocyte/macrophage morphology and increased expression of differentiation-associated antigens, e.g. CD11b, CD11c, CD14 and CD18. The growth-inhibitory response to cytokines involved in the activation and differentiation of monocytes, IFN-gamma, TNF-alpha, IL-1 beta, IL-6 and GM-CSF, was normal. Our results suggest that the U-937-1SF subline can be used as a serum-free model system for studies on various aspects of monocyte differentiation.