The role of histocompatibility (HLA) antigens in asbestosis

Histocompatibility antigens on the A, B and C loci have been studied in 172 asbestos workers, 92 of whom had radiographic evidence of asbestosis and 80 of whom had normal radiographs. Within each population, 77 were selected who matched for age, sex, duration from first exposure, duration of exposure and approximate heaviness of exposure. Results were also compared with 174 normal unexposed volunteers. No differences of statistical significance were found in the frequency of histocompatibility antigens tested when the matched or the total population of asbestos workers with and without asbestosis were compared. There was, however, a consistent trend of increase in B27 amongst those with asbestosis (11%) and this reached conventional significance (P < 0.05) when the 92 asbestotics were compared with the whole group having normal radiographs (asbestos workers 5.0% and volunteers 5.2%). Amongst the group having asbestosis, those with HLA-B27 had a significantly shorter exposure to the dust (13.5 years) compared with those without asbestosis (22.3 years), although the mean radiographic profusion score for the two categories was similar. No statistical differences could be found when B5, B8 and B12 were analysed in a similar way, but there was a trend suggesting that B5 was less frequent amongst a small group of cases showing radiographic progression over a three-year follow-up, compatible with the suggestion that this antigen might be linked with with some protective effect.