Generation of HER-2/neu-specific cytotoxic neutrophils in vivo: efficient arming of neutrophils by combined administration of granulocyte colony-stimulating factor and Fcgamma receptor I bispecific antibodies.
Abs are able to induce inflammatory antitumor responses by recruiting IgG Fc receptor (FcgammaR)-bearing cytotoxic effector cells. We recently described the capacity of the high affinity FcgammaRI (CD64) to trigger cytotoxic activity of neutrophils (PMN) during granulocyte CSF (G-CSF) treatment. To take advantage of FcgammaRI as a cytotoxic trigger molecule on PMN, two Ab constructs were prepared. We show that a chimeric human IgG1 Ab (Ch520C9) and an anti-FcgammaRI bispecific Ab (BsAb; 22x520C9), both directed to the proto-oncogene product HER-2/neu, interact with FcgammaRI. In addition, both Ab constructs mediate enhanced lysis of HER-2/neu-expressing tumor cells by G-CSF-primed PMN. However, engagement of FcgammaRI by Ch520C9 was inhibited by human serum IgG, thereby abrogating the enhanced Ch520C9-mediated cytotoxicity. BsAb 22x520C9, which binds FcgammaRI outside the ligand binding domain, effectively recruits the cytotoxic potential of FcgammaRI on G-CSF-primed PMN regardless of the presence of human serum. These results indicate that under physiologic conditions, serum IgG impairs activation of FcgammaRI-mediated cytotoxicity by conventional antitumor Abs. The IgG blockade can be circumvented with anti-FcgammaRI BsAbs. Using human FcgammaRI transgenic mice we demonstrate that BsAb 22x520C9 is able to engage FcgammaRI in vivo. BsAb 22x520C9 injected i.v. was readily detected on circulating PMN of G-CSF-treated transgenic animals. In addition, we showed that PMN remain "armed" with BsAb 22x520C9 during migration to inflammatory sites, and that after isolation such PMN specifically lyse HER-2/neu-expressing tumor cells. These results point to the possibility of targeting anti-FcgammaRI BsAbs to G-CSF-primed PMN in vivo, endowing them with specific anti-tumor activity.
Heijnen
I A
IA
Department of Immunology, University Hospital Utrecht, The Netherlands.
Rijks
L J
LJ
Schiel
A
A
Stockmeyer
B
B
van Ojik
H H
HH
Dechant
M
M
Valerius
T
T
Keler
T
T
Tutt
A L
AL
Glennie
M J
MJ
van Royen
E A
EA
Capel
P J
PJ
van de Winkel
J G
JG
D000818:Animals; D018033:Antibodies, Bispecific / Q000494:pharmacology*; D000920:Antibody-Dependent Cell Cytotoxicity; D016179:Granulocyte Colony-Stimulating Factor / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D009504:Neutrophils / Q000276:immunology*; D000090063:Proto-Oncogene Mas; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology*; D017452:Receptors, IgG / Q000008:administration & dosage / Q000276:immunology*; D011994:Recombinant Proteins / Q000378:metabolism; D014407:Tumor Cells, Cultured
D018033:Antibodies, Bispecific; D016179:Granulocyte Colony-Stimulating Factor; D000090063:Proto-Oncogene Mas; D018719:Erb-b2 Receptor Tyrosine Kinases; D017452:Receptors, IgG; D011994:Recombinant Proteins; C000715470:MAS1 protein, human