IgG2b-dependent down regulation of the LPS-induced PFC-response and its blockade by Fc gamma 2bR protein.
Fc gamma receptor (Fc gamma R)-dependent immunoregulation by murine heat-aggregated (HAgg) IgG subclasses on the bacterial lipopolysaccharide (LPS)-induced plaque forming cell (PFC) response to trinitrophenylated sheep red blood cell (TNP-SRBC) antigen and the competitive effect by Fc gamma 2bR-protein on the down regulation by HAgg-IgG2b were studied in murine T-cell-deprived spleen cell cultures. HAgg-IgG1 and HAgg-IgG3 enhanced the PFC response, but HAgg-IgG2b strongly suppressed the LPS-induced PFC response. HAgg-IgG1 could not compete with the suppressive effect of HAgg-IgG2b. The HAgg-IgG2b seemed to act on both macrophages (M phi) and B-cells, because the cell cultures that had been reconstituted with HAgg-IgG2b-pretreated M phi and untreated B-cells and vice versa showed poor PFC responses. The suppression induced by HAgg-IgG2b on the LPS-induced PFC response in the T-cell-deprived cultures was abolished by the addition of phospholipase C (PLC)-treated Fc gamma 2bR protein at the early stage of the culture. The mechanisms by which HAgg-IgG2b suppress the LPS-induced PFC response and PLC-treated Fc gamma 2bR protein restores this response were discussed.
Saito-Taki
T
T
Department of Microbiology, Jichi Medical School, Tochigi-ken, Japan.
Suzuki
T
T
Nakano
M
M
D000727:Androgen-Binding Protein; D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects; D002352:Carrier Proteins / Q000494:pharmacology; D002449:Cell Aggregation / Q000187:drug effects; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects / Q000276:immunology*; D007074:Immunoglobulin G / Q000494:pharmacology*; D007166:Immunosuppressive Agents / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D049294:Phospholipid Transfer Proteins; D012756:Sheep; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
D000727:Androgen-Binding Protein; D002352:Carrier Proteins; D007074:Immunoglobulin G; D007166:Immunosuppressive Agents; D008070:Lipopolysaccharides; D049294:Phospholipid Transfer Proteins