Primary biliary cirrhosis among atomic bomb survivors in Nagasaki, Japan

Despite rapid progress in methods for analyzing radiation effects, much rem ains to be learned about the mechanisms and processes of radiation-induced immunological dysfunction. Among 17,899 sera obtained from atomic bomb surv ivors in Nagasaki, Japan, sera from 484 participants who complied with a re examination for alkaline: phosphatase (ALP) were tested for antimitochondri al antibody (AMA) by indirect immunofluorescence, and autoantibodies agains t 2-oxo-acid dehydrogenase complex (2-OADC) by immunoblotting to investigat e the prevalence of primary biliary cirrhosis (PBC). Of these 484 sera, 28 (5.8%) were seropositive for AMA. The 483 participants were divided into th ree groups according to distance from the hypocenter: 72 who were exposed w ithin 1999 m (closest group), 368 from 2000 to 5999 m (intermediate distant group), and 44 outside 6000 m (distant group). The positivity rates for AM A in these three groups were 6/72 (8.3%), 22/368 (6.0%), and 0/44 (0%), res pectively (P = .08). Furthermore, high titers ( > 1:320) of AMA were observ ed in 3/6 (50%) AMA-positive sera from the closest group, in contrast to 4/ 22 (18%) from the intermediate distant group. although there was no signifi cant correlation between AMA titer and distance from the hypocenter (P = .0 7). Of these 28 AMA-positive sera, 11 (39%) were from participants who had already been diagnosed with PBC, and 25 (89%) contained antibodies against at least one component of 2-OADC enzymes by immunoblotting. Therefore, the prevalence of PBC was estimated to be at least 615 cases per million (792 p er million women). Our results suggest that the prevalence of PRC in atomic bomb survivors in Nagasaki is higher than that reported for the general po pulation in Japan. and a further survey of the environmental factors, inclu ding radiation exposure, that predispose to PBC would be needed for underst anding this disease of unknown etiology. (C) 2001 Elsevier Science Inc. All rights reserved.