Effect of protein A on staphylococcal opsonization.

P. K. Peterson, J. Verhoef, L. D. Sabath, P. G. Quie

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To study the effect of wall protein A on bacterial opsonization, phagocytosis of 10 strains of Staphylococcus aureus with high and low protein A contents was measured. Those strains that contained the highest concentrations of protein A were phagocytized by human neutrophils at a slower rate than strains with little or no protein A when normal human serum and purified immunoglobulin G (IgG) were used as opsonic sources. When IgG-deficient serum was used as an source, however, protein A-rich strains were phagocytized more rapidly than protein A-deficient strains. Extracellular (purified) protein A decrease the opsonic activity of all sera tested including IgG-deficient serum. It is proposed that when IgG is not present in the opsonic medium, cell wall protein A is capable of activating complement at the bacterial surface and thereby opsonization is promoted.
Original languageUndefined/Unknown
Pages (from-to)760-764
Number of pages5
JournalInfection and Immunity
Issue number3
StatePublished - 1977


  • Bacterial Proteins
  • Cell Wall
  • Complement System Proteins
  • Humans
  • Leukocytes/im [Immunology]
  • Phagocytosis
  • Staphylococcus aureus/im [Immunology]

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