Induction of Fc (IgG) receptor(s) by simian cytomegaloviruses in human embryonic lung fibroblasts.

Abstract

Human embryonic lung (HEL) fibroblasts infected with simian cytomegalovirus (SCMV) were found to bind nonspecifically to the Fc portion of human immunoglobulin (Ig) G (IgG). Binding of IgG to SCMV-infected HEL fibroblasts, but not to uninfected HEL cells, was visualized as cytoplasmic fluorescence by the indirect immunofluorescence test, regardless of the presence of anti-CMV antibodies. The receptor(s) reacted with the IgG class of different species, but not with IgM and IgA. The purified Fc fragment reacted with the receptor(s), but the Fab fragment reacted poorly. The reaction was blocked by pretreatment of infected cells with the Fc fragment, but was not blocked with the Fab fragment. The appearance of the Fc receptor(s) required RNA and protein synthesis, whereas a requirement for DNA synthesis remains to be answered by a more sensitive assay. The development of the Fc receptor(s) was inhibited by 2-deoxy-D-glucose, thus indicating that the Fc receptor(s) may be a glycoprotein(s). The Fc receptor(s) was induced by all strains of SCMV tested so far. These included one laboratory strain (GR2757), four fresh isolates from primary kidney cell cultures of African green monkeys, and four fresh isolates from the salivary glands of the Macaca monkeys captured from the wild in Japan.