Agalactosyl IgG, antibodies to heat shock proteins, and acute rheumatic fever.

In rheumatoid arthritis an increased proportion of the N-linked oligosaccharides on serum IgG terminate with N-acetylglucosamine (agalactosyl IgG). It has recently been shown that group A streptococcal cell wall peptidoglycan/polysaccharide complex may be used to raise monoclonal antibodies which bind to this glycoform of IgG. Patients with rheumatoid arthritis also have increased levels of antibody to the 65 kD and 70 kD families of heat shock proteins, particularly to a bacterial (Mycobacterium bovis) homologue of heat shock protein hsp65. Streptococci must contain similar heat shock proteins. Acute rheumatic fever follows infection with group A streptococci, and these organisms might theoretically evoke antibody to heat shock proteins or changes in the levels of agalactosyl IgG, which is antigenically cross reactive with their cell walls. It is shown here that serum samples from patients with acute rheumatic fever do not differ from those from normal children by these criteria.