IGA PROTEASE PRODUCED BY STREPTOCOCCUS-SANGUIS AND ANTIBODY-PRODUCTION AGAINST IGA PROTEASE IN PATIENTS WITH BEHCETS-DISEASE

The production of IgA protease in twelve strains of Streptococcus sang uis isolated from patients with Behcet's disease (BD) was examined, Pr otease activity was detected in 10 out of 12 strains, The protease was purified from one representative strain, S. sanguis 113-20, by employ ing Rotofor and DEAE-Sephacel chromatography, The molecular mass of th e purified protease was approximately 100 kDa, and it cleaved the prol ine-threonine site of the IgA, Both IgG and IgA titers against the cel ls (113-20) and the purified IgA protease in the sera of BD patients a nd healthy controls, 36 each, were assayed, The IgG titers against the cells and protease were not significant in the BD patients or control s, but the IgA titers against the cells and protease in the BD patient s were significantly higher than those of the controls, These data ind icate that the BD patients are infected with IgA protease-producing S. sanguis strains, which cause an increase of IgA titer against these o rganisms and IgA protease antigen. Since the organisms can proliferate in BD patients for a long period of time (years), it seems that IgA a ntibodies cannot effectively eliminate the organisms.