Anti-neutrophil cytoplasmic autoantibody (ANCA) profiles in propylthiouracil-induced lupus-like manifestations in monozygotic triplets with hyperthyroidism.

We describe the ANCA profile of two monozygotic triplets (A and B) treated with propylthiouracil (PTU) for hyperthyroidism who developed LE-like manifestations. Triplet C also developed hyperthyroidism but was not treated with PTU and never experienced LE-like symptoms. Triplet A and B showed a marked rise in P-ANCA titer to 1:1280 after PTU was introduced whereas triplet C never had a titer higher than 1:80. Consecutive sera were investigated for ANCA to six different neutrophil granule proteins. Triplet A and B, but not C, both developed a strongly positive elastase-ANCA. Our results confirm the importance of a genetic factor influencing the susceptibility to drug-induced LE.