Experimental suprabasal bulla formation in organ cultured human skin with low calcium medium

The effect of calcium ions on human epidermis was studied using an organ culture system. Acantholysis-like suprabasal cleft formation was constantly observed within 12 hours, when normal human skin explants were cultured in medium with less than 0.1 mM of calcium ions. This change resembled that induced by pemphigus serum observed with light or electron microscopy. This effect was greatly enhanced by the presence of fetal calf serum and was reversed when normal calcium concentrations were added back. Pemphigus antigen was not reduced in the explants. This change was inhibited by alpha 2-macroglobulin, a proteinase inhibitor with a wide spectrum. Biochemical study did not show apparent change of glycoproteins in epidermal cells. Therefore, it is most likely that this phenomenon is induced by some proteinase(s) which is(are) released from epidermal cells in the presence of fetal calf serum and activated at very low calcium ion concentration. Furthermore, this system is considered to be more useful than the cell culture system to study the effect of calcium ions in organized epidermis.