Serum antibodies to group A streptococcal extracellular and cell-associated antigens in Egyptians with post-streptococcal diseases

We investigated serum antibodies to a comprehensive array of group A strept ococcal antigens and superantigens in Egyptian subjects. Antibodies to Stre ptococcus pyogen es cell-associated proteins and to proteins released by ra pidly dividing S. pyogenes were compared in four patient groups with differ ent post-streptococcal diseases and in healthy controls. Enzyme-linked immu nosorbent assays showed that total Ig and IgG to extracellular antigens wer e significantly higher in patients with acute rheumatic fever (ARF) compare d to healthy controls, but no differences were found in either total Ig or IgG titres to cell-associated proteins between any of the groups. Western b lotting showed that multiple extracellular and cell-associated antigens, co vering a wide range of molecular masses, were recognised by all sera, inclu ding healthy controls. No evidence was obtained for putative dominant antig ens associated with any disease group, although a low molecular mass cell-a ssociated protein (approximately 4 kDa) was clearly recognised by two-third s of subjects irrespective of disease status. These findings demonstrate th at raised serum Ig and IgG titres to extracellular, but not cell-associated , S. pyogenes antigens are a feature of ARF in this population, and suggest that multiple S. pyogenes antigens contribute to this response. (C) 2001 F ederation of European Microbiological Societies. Published by Elsevier Scie nce B.V. All rights reserved.