Interaction of Human Polyclonal IgE and IgG from Different Species with Protein A from Staphylococcus aureus: Demonstration of Protein‐A‐reactive Sites Located in the Fab₂ Fragment of Human IgG

Abstract

The peptic fragments F(ab')2 and Fc" of human polyclonal IgE were tested by the SpA-IgE radioimmunoassay for interaction with protein A from Staphylococcus aureus. The Fab'2 epsilon fragment but not the Fc" epsilon fragment retained the ability to react with protein A. IgG preparations from different species were tested for ther capacity to inhibit the reaction between 125I-IgE and protein A. IgG preparations from man and the dog, pig, guinea-pig and rhesus monkey were all potent inhibitors whereas those from the rabbit, rat, sheep, horse, cow, goat and mouse were very poor inhibitors. The inhibition of the binding of 125I-IgE to protein A by Fab'2 gamma fragments, but not by Fc gamma fragments, suggests a novel type of interaction of protein A with immunoglobulins.

Bacterial Immunoglobulin Superantigen Proteins A and L Activate Human Heart Mast Cells by Interacting with Immunoglobulin E

“…ϩ had no effect. This suggests that protein A's releasing activity depends on binding to an Ig structure located in the V H 3 domain, a fragment common to all Ig classes and subclasses (23,25,52,56). The releasing activity of protein L-containing bacteria, such as P. magnus strain 312, and soluble protein L appears to be mediated by interaction with IgE present on HHMC.…”

“…We first studied the effect on protein A-induced HHMC activation of molecules that show only Fc␥-protein A reactivity, such as RIgG, and those with both Fc␥ and F(abЈ) 2 reactivity, such as HIgG (23,52). HIgG dose dependently inhibited protein A-induced histamine release, whereas RIgG, which does not bind the alternative site of protein A (25), had no such effect (Fig. 4A).…”

In vitro synthesis of IgM rheumatoid factor in response to STAPHYLOCOCCUS AUREUS, by lymphocytes from healthy adults

“…SAC appears to be a particularly potent stimulator of RF production. While it is assumed that SAC has a direct effect on responsive lymphocytes, the mechanism of action may be related to an interaction between SAC and the F(ab')* and/or the Fc portion of IgG (13,14), either on the surfaces of the B cells or in the culture supernatant after IgG secretion. Theoretically, it is possible that this interaction mod-ifies the IgG molecule in such a way that it more readily stimulates RF response.…”

Prevalence of Genes Encoding Pyrogenic Toxin Superantigens and Exfoliative Toxins among Strains of Staphylococcus aureus Isolated from Blood and Nasal Specimens

“…As a consequence of the availability of commercial tests, these studies were restricted to five classical enterotoxins: SEA to SED and TSST-1. Furthermore, the immunological methods used thus far are known to be limited in sensitivity and specificity (6,16,32). To date, no valid data are available concerning the prevalence of the more recently described enterotoxins in S. aureus isolates derived from clinical specimens.…”