Low-dose Oral Methotrexate Induces Apoptosis of Tissue Eosinophils in Bullous Pemphigoid

Abstract

We have shown previously that eosinophils are abundant in blood and tissue in bullous pemphigoid and that they rapidly disappear, without sign of necrosis, during methotrexate therapy. The aim of the present study was to investigate the role of apoptosis in this phenomenon. The terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labelling method for detecting apoptosis was used, combined with immunohistochemical detection of eosinophils before and during oral methotrexate. The numbers of apoptotic eosinophils were compared using light microscopy. Eosinophil apoptosis was significantly higher in skin after one week of methotrexate therapy and the number of eosinophils was reduced. The results indicate that methotrexate therapy induces apoptosis of the tissue eosinophils in bullous pemphigoid.