[Experimental epithelioid cell granuloma formation in Lewis rats induced by injection of cell wall fragments derived from alpha-streptococcus--etiologic relationship between bacterial cell wall and sarcoid granuloma].

We observed the presence of epithelioid granulomas in follicles near lacunae in the tonsils from patients with active sarcoidosis. Bacteria isolated in these tissues were mostly alpha-streptococci. The present study was undertaken to determine whether alpha-streptococcus can induce granuloma formation. Streptococcal cell wall (SCW) fragments were injected into the foot pads of female Lewis rats. Epithelioid granulomas were abundantly formed in popliteal lymph nodes when SCW aqueous suspension was injected four times. SCW antigens were detected in macrophages in the granuloma but not in epithelioid cells, by immunoperoxidase method. These findings suggest that macrophages transform into epithelioid cells after phagocytosis and digestion of SCW, and that components of bacterial cell wall such as SCW may induce the granuloma formation in sarcoidosis.