Fcgamma receptor-mediated immune phagocytosis depends on the class of FcgammaR and on the immunoglobulin-coated target cell.
OBJECTIVE
Three human Fcgamma receptors (FcgammaR) are known to mediate immune phagocytosis. A variety of different phagocytic assays have been described, but their comparability is complicated by the use of different effector cells and different antibody-coated target cells. The aim of this study was to determine the influence of these variable components on the FcgammaR-mediated phagocytosis.


METHODS
We sensitized human red blood cells (RBC) with polyclonal human anti-D (huaD), or with human monoclonal anti-D of the isotypes IgG1 (huIgG1) or IgG3 (huIgG3). Sheep RBC coated with rabbit immunoglobulin (RBC-RAS) were also used. Monocytes or polymorphonuclear neutrophils (PMN) were incubated with different FcgammaR-specific antibodies or their F(ab')2 fragments to determine the contribution of the different FcgammaRs on these effector cells in the phagocytic process of different antibody-coated target cells.


RESULTS
huaD-RBC and huIgG1-RBC were preferentially ingested via the FcgammaRI on monocytes and, to a minor extent, also by the FcgammaRII. PMN ingested these target cells only after induction of the FcgammaRI by interferon-gamma (IFN-gamma). huIgG3-RBC extensively formed rosettes with monocytes but were seldom ingested. RAS-RBC phagocytosis was induced primarily via the FcgammaRI on monocytes and was mediated by the FcgammaRII on PMN.


CONCLUSIONS
When performing phagocytosis assays with different effector and target cells, one has to take into account that phagocytosis is mediated by different FcgammaR, making comparability of these assays more difficult.
Flesch
B K
BK
Institute of Transfusion Medicine, Universitätsklinikum Kiel, Germany. flesch@transfusion.uni-kiel.de
Vöge
K
K
Henrichs
T
T
Neppert
J
J
D000818:Animals; D004912:Erythrocytes / Q000276:immunology*; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D007132:Immunoglobulin Isotypes / Q000276:immunology; D007518:Isoantibodies / Q000276:immunology*; D009000:Monocytes / Q000276:immunology; D009504:Neutrophils / Q000276:immunology; D010587:Phagocytosis / Q000276:immunology*; D011817:Rabbits; D017452:Receptors, IgG / Q000145:classification / Q000276:immunology*; D018029:Rho(D) Immune Globulin; D012756:Sheep
D007106:Immune Sera; D007132:Immunoglobulin Isotypes; D007518:Isoantibodies; C061961:RHO(D) antibody; D017452:Receptors, IgG; D018029:Rho(D) Immune Globulin