A light and electron microscopic study of the distribution of gold sodium thiomalate in the rheumatoid synovial membranes

The synovial membranes from 16 rheumatoid patients treated with intramuscular injections of gold sodium thiomalate were observed by light and electron microscopy with special reference to the distribution of gold particles in the tissue. 1) Light microscopic study revealed that the gold demonstrated as cytoplasmic granules by OKAMOTO'S histochemical method were contained in the synovial lining cells and in the macrophages around lymph-follicles and blood vessels in the subsynovial layer. In the well-developed villi on the surface of rheumatoid synovial membrane, large macrophages with gold granules infiltrated into the lymphoid cell accumulation of small lymph-follicles. 2) The deposition of gold in the synovial tissue increased with the increase of the doses of gold administered. 3) Electron microscopic observation indicated that gold particles are contained in the numerous lysosomes in the Type A and intermediate lining cells. The macrophages around lymph-follicles and blood vessels also possessed a large amount of gold particles gathered in the lysosomes of these cells. 4) Macrophages containing gold particles in their long cytoplasmic extensions were found often in a close contact with plasma cells of various differentiation stages. A direct cytoplasmic connection was observed between the two kinds of cells but an artifact could not be excluded. 5) The effect of gold salt in the treatment of RA was discussed from the immunological view point.