Non-positive autoimmune responses against CYP2E1 in refrigeration mechanics exposed to halogenated hydrocarbons

The aim of the study was to determine if occupational exposure to hydrofluorocarbons (HFC) and hydrochlorofluorocarbons (HCFC) generates autoimmune responses against CYP2E1. HFCs and HCFCs have replaced the chlorofluorocarbons (CFC) in e.g. refrigeration installations and air-conditioning systems. During the substitution period, refrigeration mechanics reported symptoms like asthma, influenza-like reactions, and joint troubles. These symptoms resemble those of chronic inflammatory diseases with an autoimmune component. Since exposure to structurally similar chemicals, e.g. halothane, has previously been associated with autoimmune responses and diseases, autoimmunity among the refrigeration mechanics might hypothetically explain the reported inflammatory symptoms. Serum from 44 Swedish men, occupationally exposed to halogenated hydrocarbons, was screened for antibodies against CYP2E1 with enzyme-linked immunosorbent assay. Thirty of the workers had asthma, joint problems or influenza-like symptoms whereas 14 of them had no such symptoms. They were all selected from a cohort of 280 refrigeration mechanics. Unexposed, healthy, Swedish men (n=35) constituted control group. The study was approved by the Ethics Committee at Karolinska Institutet. No increase in autoantibodies against CYP2E1 was detected among the occupationally exposed workers as compared to the unexposed controls. Further, there was no difference in antibody titer between the exposed workers with symptoms and the exposed, asymtomatic workers or the unexposed controls. The present study does not completely exclude a connection between exposure and effect but makes the relation less likely at these exposure levels.