Inhibition of antibody-dependent cellular cytotoxicity by protein a from Staphylococcus aureus
Rosenblatt, J.; Zeltzer, P.M.; Portaro, J.; Seeger, R.C.
Journal of Immunology 118(3): 981-985
1977
ISSN/ISBN: 0022-1767 PMID: 300395 Document Number: 119236
Protein A, a cell wall constituent of several strains of Staphylococcus aureus, binds strongly to the Fc portion of immunoglobulins. This investigation demonstrated that such binding can inhibit antibody-dependent cellular cytotoxicity (ADCC). The degree to which ADCC was inhibited depended upon the relative concentrations of protein A and anti-target cell antiserum. Protein A also inhibited the formation of rosettes between antibody-coated sheep red blood cells and lymphoid cells with Fc receptors. We, therefore, conclude that protein A inhibits ADCC by preventing the binding of antibody-coated target cells to Fc receptors on cytotoxic effector cells.