Studies on the Mechanism of the White Response and of the Delayed Blanch Phenomenon in Atopic Subjects by Means of Coomassie Blue

The question of peculiar vascular reactions in inflamed skin and particularly in atopic dermatitis has recently been reinvestigated and the literature on this subject has been reviewed (1). Scott (2) demonstrated acetylcholinesterase in sensory nerves and in arteriolar walls in erythematous skin and this enzyme activity was also found in the erythematous flares around acetylcholine injections and also in atopics in whom acetylcholine had produced the delayed blanch phenomenon. Davies and Lawlor (3) studied the delayed blanch by means of capillary microscopy and observed dilated capillaries in the blanched area and they attributed the blanching to the presence of edema fluid. This view was not shared by Lobitz (4) who measured the water content of tissues by a desiccation process and found that histamine caused a marked increase in tissue fluid in normal skin, while the reverse was found after injection of acetylcholine. Moreover, the decrease was greater in atopics than in normals and no increase in tissue fluid was found in the blanched area.