Effect of extracellular products of Streptococcus on macrophage Fc receptors for IgG.

The effect of the extracellular products of Streptococcus (EPS) on the receptors for Fc of IgG of dog alveolar macrophage (AM) was evaluated by the rosette test. The AM controls produced 80 per cent rosettes; those treated with EPS, a reduced number of rosettes, which was directly related with the concentration of EPS. The adhesion of EPS treated AM to glass was less than that of the AM controls. Incubation of AM with streptokinase-streptodornase did not modify the amount of rosettes. The data support the possibility that streptolysin-O is the substance which modifies, or destroys the Fc receptors, or the integrity of the cell membrane. Ouabain did not alter the capacity of the dog alveolar macrophages to form rosettes, suggesting that cellular energy is not required for the interaction between the Fc receptor and the IgG.