Binding of aggregated human beta2-microglobulin to surface protein structure in group A, C, and G streptococci

Publisher Website
Google Scholar
Abstract
A novel mammalian-microbial "short circuit" was demonstrated between aggregated human .beta.2-microglobulin and group A, C and G streptococci. Bacteria belonging to 9 gram-positive and 3 gram-negative species were tested for binding of radiolabeled .beta.2-microglobulin. All 10 individual strains of group A streptococci showed a high degree of reactivity with aggregated human .beta.2-microglobulin. Among 27 group C and 28 group G streptococci, 9 and 6 strains, respectively, were highly reactive, whereas the remaining strains showed a lower, but definite level of .beta.2-microglobulin binding. Of 11 group B streptococci, 4 were slightly positive. All strains among the other 8 species were completely negative. Simultaneous testing of A, C and G streptococci for immunoglobulin binding showed a lack of correlation between type II and III Fc reactivity and .beta.2-microglobulin binding. There was no inhibition of uptake of aggregated .beta.2-microglobulin to reactive strains when excess amounts of human immunoglobulin were added. The .beta.2-microglobulin-binding surface structure was markedly sensitive to trypsin digestion. The relative trypsin resistance of the immunoglobulin-binding protein in the digestion experiments further demonstrated the dissociation between these 2 reactivities.