Asbestos exposure correlates with alterations in circulating T cell subsets

Peripheral blood lymphocytes were analysed from 40 subjects with occupational asbestos exposure and 40 controls matched for age and smoking habits. Patients were classified by duration of exposure as short or long, and by chest radiograph as normal, pleural plaques or interstitial changes. As a group, subjects with asbestos exposure had decreased percentages of OKT3+ and OKT8+ cells and increased OKT4+/OKT8+ ratio compared to controls. Correcting for age and smoking, those with short exposure were similar to controls, while those with long exposure had decreased percentages OKT3+ and OKT8+ cells and an increased OKT4+/OKT8+ ratio. Among radiographic subgroups, those with normal radiographs were similar to controls, but those with plaques had increased circulating OKT4+ cells, and those with interstitial changes had decreased percentages OKT3+ and OKT8+ cells and OKT8+ cells/mm3, with an increased OKT4+/OKT8+ ratio. There were no differences between subjects and controls in OKT10+ cells and OKIa+ cells. There appears to be a progressive decrease in percentage OKT8+ cells and increase in OKT4+/OKT8+ ratio with increasing exposure to asbestos, as determined by length of exposure and by radiographic abnormalities.