Biochemical Acantholysis Provoked by Thiol Drugs

To the Editor.— We read with interest the article by Yokel et al¹in the October 1989 issue of theArchives, dealing with the in vitro induction of acantholysis by means of penicillamine and captopril in the absence of pemphigus autoantibody. The experiments and results reported in the article are very similar to those carried out by us, first with penicillamine²(as quoted in the article), then with captopril and thiopronine³(Fig 1) (left unmentioned), and by others⁴(also unmentioned). On the whole, these studies show that drugs containing thiol groups in their molecule (such as penicillamine, captopril, thiopronine), as well as some cyclic sulfone drugs that have a masked thiol group (eg, piroxicam), are capable of causing acantholysis without antibody mediation (biochemical acantholysis), similar to that obtained in tissue cultures added with pemphigus autoantibodies (immunological acantholysis). The proven existence of a biochemical acantholysis may well