Surface-bound immune complexes trigger transmembrane proximity between complement receptor type 3 and the neutrophil's cortical microfilaments.
To characterize the transmembrane associations participating in antibody-dependent binding, we have used resonance energy transfer (r.e.t.) microscopy to assess the molecular proximity of complement receptor type 3 (CR3) and Fc gamma R type II (Fc gamma RII) and type III (Fc gamma RIII) with microfilaments during neutrophil adherence to untreated surfaces, surfaces coated with BSA, surfaces coated with BSA/anti-BSA F(ab')2 complexes, or surfaces coated with BSA/anti-BSA rabbit IgG immune complexes. Receptors were labeled with fluorescein-conjugated antireceptor Fab fragments, whereas microfilaments were labeled with rhodamine-phalloidin. CR3-to-microfilament r.e.t. was dramatically increased in neutrophils adherent to IgG immune complex-coated surfaces but not untreated or control surfaces. However, the low level of r.e.t. between donor-labeled anti-Fc gamma RII Fab fragments and rhodamine-phalloidin was not affected by any condition including surface-bound immune complexes. Significant r.e.t. levels between Fc gamma RIII and microfilaments were not found under any condition. We suggest that CR3 plays an important role in tethering surface-attached immune complexes to the neutrophil's cytoskeleton.
Zhou
M J
MJ
Department of Biological Sciences, Wayne State University, Detroit, MI 48202.
Poo
H
H
Todd
R F
RF
Petty
H R
HR
D008841:Actin Cytoskeleton / Q000378:metabolism*; D000936:Antigen-Antibody Complex / Q000378:metabolism*; D015703:Antigens, CD / Q000378:metabolism; D000943:Antigens, Differentiation / Q000378:metabolism; D002451:Cell Compartmentation; D004735:Energy Transfer; D005455:Fluorescent Antibody Technique; D006801:Humans; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D016177:Macrophage-1 Antigen / Q000378:metabolism*; D009504:Neutrophils / Q000378:metabolism* / Q000648:ultrastructure; D011961:Receptors, Fc / Q000378:metabolism; D017452:Receptors, IgG
D000936:Antigen-Antibody Complex; D015703:Antigens, CD; D000943:Antigens, Differentiation; D046911:Macromolecular Substances; D016177:Macrophage-1 Antigen; D011961:Receptors, Fc; D017452:Receptors, IgG