Cutaneous mast cells are altered in normal healthy volunteers sitting in front of ordinary TVs/PCs - results from open-field provocation experiments

Background: Considerable controversy has surrounded the question of possibl e biological responses to electromagnetic fields (EMFs) generated from visu al display terminals (VDTs), such as personal computers (PCs) and ordinary television sets (TVs). The cellular and molecular mechanisms for such poten tial harmful health hazards have not yet been understood, although clues fr om the literature include mast cells and histamine. The aim of this study w as therefore to investigate possible biological mast cell responses to TV/P C screens. Methods: Using the indirect immunofluorescence technique, we studied the pr esence of histamine-containing mast cells in the dermis of healthy voluntee rs. Cutaneous biopsies taken before and after exposure to ordinary TV/PC sc reens for 2 or 4 h were investigated in 13 healthy subjects. Results: Our present in vivo study indicates that normal cutaneous mast cel ls could be altered by exposure from ordinary TV/PC screens. To our great s urprise, we found the number of mast cells in the papillary and reticular d ermis to increase, to varying degrees, in 5 out the 13 subjects after such an exposure. A migration of mast cells towards the uppermost dermis appeare d as the most important event. Thus, the normally upper "empty zone" of the dermis disappeared, and instead, a higher density of mast cells were found in this zone. These cells also seemed to have a tendency to increase in nu mber towards the epidermal-dermal junctional zone and some of them lost the ir granular content and the cytoplasm shrunk (=degranulation). These findin gs could only be seen in the exposed skin. Two of the 13 cases instead show ed a decrease in mast cell number, but the shift in mast cells towards the upper dermis was still visible. Twenty-four h after the provocation, the ce llular number and location were normalized in all subjects. Conclusions: By definition, normal healthy volunteers are assumed not to re act to a TV/PC screen provocation. To our great surprise, this proved not t o be true. The present results might lay a foundation to understand the und erlying cause of so-called "screen dermatitis" with special reference to ma st cells. However, blind or double-blind experiments using patients ought t o be further investigated in order to find out the exact cause for the obse rved changes. Such causes include the effects of surrounding airborne chemi cals, stress factors, etc. (C) Munksgaard 2001.