Relationship between the Fc receptor for IgG and the specific associated antigen of the pluripotential leukaemia cell line, K-562.

The cells in the K-562 line have been shown to express Fc receptors as demonstrated by rosette formation with sheep erythrocytes (E) sensitized with haemagglutinin (EA). Rosette formation is inhibited by prior incubation of the cells with goat or monkey anti-K-562 serum, gammaglobulin fraction, or Fab fragments. Alkaline aggregated human IgG also inhibits rosette formation. Furthermore, formed rosettes can be dissociated by goat anti-K-562 gammaglobulins indicating that the binding of the ligand to one entity interferes with the binding to the other. We also found that treatment of K-562 cells with specific anti-K-562 globulin leads to patching and capping of surface antigen. After patching and capping, the cells will not form rosettes. These findings suggest that the Fc receptor and the K-562 associated antigen are either located very close to one another or are the same entity.