A comparison of morphoea and lichen sclerosus et atrophicus in vitro: the effects of para-aminobenzoate on skin fibroblasts.

To study the effects of para-aminobenzoate on the dermis, fibroblast cell lines derived from lesions of lichen sclerosus et atrophicus, from morphoea and from normal skin were incubated with Potaba in vitro. Monolayer cultures containing Potaba showed a dose-dependent inhibition of proliferation beginning at 1,000 micrograms/ml with total inhibition at 10,000 micrograms/ml. Mean ID50 values for the three groups were not significantly different. There was a similar dose dependent inhibition of glycosaminoglycan secretion in all 3 groups, except at 10,000 micrograms/ml where secretion by lichen sclerosus et atrophicus and morphoea fibroblasts was significantly more inhibited than normal lines. Inhibition of the glycosaminoglycan secretion at 10-1,000 micrograms/ml was a direct effect of the drug rather than an indirect effect of changes in cell density, and lichen sclerosus et atrophicus fibroblasts produced about 40% more GAG than the morphoea or normal lines growing at similar densities. Collagen synthesis was increased in both lichen sclerosus et atrophicus and morphoea cell lines, with increased non-collagenous protein in morphoea lines. These results confirm that there are differences between lichen sclerosus et atrophicus and morphoea, and suggest glycosaminoglycan secretion as a possible target for the therapeutic action of Potaba.