[Research trend for pathogenesis of sarcoidosis--streptococcal cell wall component (SCW)].

In search for the pathogenetic factors, we have found the following: 1) Chronic bacterial foci in the upper airway is showing adverse effect on clinical course of sarcoidosis. Alpha-streptococcus is mainly detected. 2) The prevalence of chronic tonsillitis in sarcoidosis is high if compared with that among Japanese adults examined by rhinolaryngologists. 3) The development of noncaseating epithelioid granulomas is reported after injections of an aqueous suspension of alpha-streptococcal cell wall (SCW) fragments into susceptible Lewis female rats. 4) Both protracted clinical course in sarcoidosis and higher responsiveness to SCW antigen are related to HLA-DR4, DR9 and DRw8. These results suggest that in sarcoidosis significance of persistence of antigen in upper respiratory tract and the significant correlation between SCW binding to Ia and immunogenicity, implicated by Schaeffer's, are seen.