In recent years, with the aging of patients with
pneumoconiosis,
autoimmune diseases as a complication have been observed. One of the reasons for this may be that
autoimmune diseases are prone to develop among the elderly. On the other hand, it has been reported that dust itself, such as
silica for example, has adjuvant effect. A review of the recent literature published in Japan and abroad was made to clarify the relationship between
pneumoconiosis and
autoimmune diseases and the following results were obtained. 1) Disorders which accompany
pneumoconiosis: Scleroderma,
rheumatoid arthritis,
systemic lupus erythematosus (SLE), and disorders of the kidney and liver have been reported. In Japan, about 30 cases of
pneumoconiosis accompanied with
autoimmune diseases have been reported. In many of the reports, patients with
pneumoconiosis and scleroderma have a past history of exposure to
silica. In both case studies and case control studies, patients with
rheumatoid arthritis and history of
silica exposure are prone to develop
pneumoconiosis. 2) Immunological studies of patients with
pneumoconiosis: As for humoral immunity, elevation of polyclonal
gamma-globulin, especially
IgG, has been often reported together with high positive rate of
autoantibodies such as
antinuclear antibodies. In cellular immunity, decreased delayed type skin reaction and decreased CD4/8 ratio have been reported. In
human leukocyte antigen (HLA) typing the elevated frequency of DR4 has been reported. In the study of BAL increased production of
superoxide anion O2- by alveolar macrophages has been observed. 3) EXPERIMENTAL STUDIES:
Silica is well known for its toxicity to cells and also for its adjuvant effect. In the German Democratic Republic, patients with scleroderma and history of long term
silica exposure are recognized as patients with
occupational disease even though
pneumoconiosis is not clearly demonstrated on
X-ray film. It is difficult from this review to nrake a definite conclusion regarding the relation between
silicosis and
autoimmune diseases. There is a need to repeat this review of the literature on
autoimmune diseases and
pneumoconiosis in the near future.