Studies On The Etiology Of Sarcoidosis

Sarcoidosis is a multisystemic disorder characterized by the presence of non-caseating granuloma. Its etiology remains unknown. It is considered that both extrinsic and intrinsic factors may be involved in the development of the disease on account of the great difference in its prevalence rate in different parts of the world, therefore, etiological factors in both regards are investigated. The activation and proliferation of T helper lymphocytes as well as macrophages in the foci of lesion in sarcoidosis indicate the nature of enhancement of cellular immune of the disease. It was demonstrated that the activation of T helpers depends human leukocyte antigen â…¡ (HLA- â…¡ ) , especially HLA-DR. The relationship between HLA-DR and the susceptibility of the disease as well as the clinical manifestation of 55 cases of sarcoidosis were studied by allele group specific polymerase chain reaction (PCR) technique. Besides, since Jacob proposed that Borrelia burgdorferi (Bb) might be the e-tiological agent of sarcoidosis in 1989, no confirmative evidence has yet been raised. The study of Bb antibodies was done mainly on the sera in the past, thus it can not disclose the status of the tissues; therefore, in situ PCR technique was applied to the granulomatous tissues of 23 cases of sarcoidosis.The results are as follows; (1). The gene frequency of HLA-DR5 increased greatly in patients of sarcoidosis than that of the healthy controls. (2). The absence of positive Bb in all of the specimens of granulomatous tissue of sarcoidosis.It is concluded that : (1). HLA-DR5 antigens may be relevant to the suscepti-biliby of sarcoidosis. (2). Bb might not be the causal agent of sarcoidosis.