Article

Identification of the site on IgG Fc for interaction with streptococci of groups A, C and G.

Department of Rheumatology, University Hospital of Lund, Sweden.
Immunology (Impact Factor: 3.74). 01/1988; 62(4):523-7.
Source: PubMed

ABSTRACT The interaction between living groups A, C and G streptococci and IgG Fc was studied using human IgG, IgG Fc and IgG Fc-intermediate (Fci) fragments, chemically modified human IgG and fragment D of staphylococcal protein A (SPA). Diethylpyrocarbonate modification of His or N-acetylimidazole modification of Tyr of human IgG resulted in the loss of its capacity to inhibit the binding of radiolabelled human IgG Fc to the group A streptococci types M1 and M55, and to the group C strain SC-1, indicating that the amino acids His and Tyr are involved in the binding. Lys seems not to participate in the binding of IgG to these bacteria, however, since reductive methylation of Lys did not reduce its inhibitory capacity. Fragment D of SPA also inhibited the binding of radiolabelled human IgG Fc to strains M1, M55 and SC-1. We have previously shown that these bacteria do not bind to IgG fragments consisting of only the C gamma 2 or C gamma 3 domains. On the basis of these results, and the known relative positions in space of the His and Tyr residues on IgG Fc, it is speculated whether streptococci with IgG Fc receptors, like SPA and rheumatoid factors, interact with IgG in the interface between the C gamma 2 and C gamma 3 domains and involve His 435 and one or more of Tyr 436, His 433 and His 310. The similarities in binding sites on IgG for RFs and these bacterial Fc binding proteins suggest structural similarities between them that may be relevant to the production of rheumatoid factors in rheumatoid arthritis.

Full-text

Available from: Francis Nardella, May 23, 2015
0 Followers
 · 
72 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A receptor binding the Fc region of equine immunoglobulin G (IgG) has been isolated from a heat-extracted preparation of a clinical isolate of Streptococcus zooepidemicus. This Fc receptor has a Mr of 45 x 10(3) and was occasionally seen as an apparent trimer of Mr 130 x 10(3). Antibodies prepared in horses against the receptor could be adsorbed to and eluted from whole live bacteria, confirming the surface location of this protein. Another 11 isolates of S. zooepidemicus from horses with pneumonia, abscesses or endometritis were tested for Fc-receptor activity. Although the Mr of the Fc receptors varied among isolates, their antigenicity was conserved. Thus, the Fc receptor is an attractive candidate for application in the diagnosis of, or protection against, infections with S. zooepidemicus.
    Journal of Medical Microbiology 03/1989; 28(2):137-41. DOI:10.1099/00222615-28-2-137 · 2.27 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A gene bank of Peptostreptococcus magnus DNA was established using an E. coli host-vector system. Western blot analysis identified a clone expressing protein L which bound to the light chain of human immunoglobulins. DNA sequence determination and analysis revealed an open reading frame of 992 amino acids, giving a theoretical secreted protein of 106 kD with a pl of 4.67.
    DNA Sequence 02/1994; 4(4):259-65. DOI:10.3109/10425179409020850 · 0.41 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The pathogenesis of acute poststreptococcal glomerulonephritis (APSGN), a major nonsuppurative complication of group A streptococcal (GAS) throat or skin disease, remains unclear. During the years, various theories based on certain streptococcal extracellular factors, as well as immunological mimicry between streptococci and renal tissue, have been forwarded. We earlier reported that many clinical GAS isolates with documented nephritogenic capacity show non-immune binding of monomeric or aggregated IgG. Moreover, in a rabbit model of APSGN we obtained evidence for an important role of streptococcal IgG Fc binding proteins (IgGFcBPs) belonging to the M family surface proteins; thus, hyperimmunization by whole IgGFcBP-positive streptococci was shown to induce renal glomerular changes with deposition of IgG and complement C3, resembling the picture recorded in human APSGN. These typical renal changes were always preceded by the appearance of circulating anti-IgG antibodies. In the present work, using the same rabbit model, each of two purified IgGFcBPs, isolated from type M22 GAS, were found to elicit glomerular degenerative damage comparable to that caused by whole bacteria, as well as formation of anti-IgG. In addition, the induction by whole streptococci (type M1) of experimental APSGN was inhibited by the i.v. administration of purified human or rabbit IgG Fc, but not Fab, fragment, supporting the importance of Fc-mediated mechanisms in causation of glomerulonephritis. We propose that anti-IgG antibody, induced by streptococcal IgGFcBP, facilitated renal accumulation of IgG-containing complexes, which in turn triggered complement deposition and proinflammatory cascades. Further studies on the possible beneficial effect of IgG Fc fragment in APSGN should be of interest.
    Apmis 03/2012; 120(3):221-30. DOI:10.1111/j.1600-0463.2011.02826.x · 1.92 Impact Factor