Atypias of bronchiolar epithelium associated with 6-mercaptopurine (6-MP) and triethylene melamine (TEM).An experimental study

Abstract

The pathologic and experimentally induced epithelial atypias in the lung associated with 6‐MP and TEM were investigated. Twenty‐five rabbits were given 12.5 mg of 6‐MP per week and 25 rabbits were given 1.25 mg of TEM per week. The drugs were inserted directly in the stomach by a nasal‐gastric tube. Five additional rabbits were given combined doses of both drugs per week. A control group of 50 rabbits was maintained on a standard diet. TEM produced the highest incidence of basal cell atypia (44%) but the incidence of squamous cell atypia was approximately the same in the 6‐MP and TEM series (4%). The peak incidence of atypias in both series occurred in the 3 to 6‐month period. Combined administration of 6‐MP and TEM did not produce any demonstrable additive effects on bronchiolar epithelium. A relatively high incidence of plumonary vascular hyperplasia was associated with both agents (40% with 6‐MP, and 20% with TEM). The author suggests that local anoxia may be an important contributing factor in the experimental production of epithelial atypias. The experimentally induced epithelial atypias were basically similar to those noted in humans after treatment with various antileukemic agents.