Macrophage tumor cell interaction is enhanced by C3 fragments.
We tested the capacity of Lewis Lung carcinoma cells (3LL) to activate the alternative pathway of complement and to bind the C3 fragments on the plasma membrane. C3 fragments were detected by cytofluorometry and by immunoblotting. In time, the fixed C3b molecules were further cleaved into iC3b. The presence of C3b/iC3b on the target enhanced the formation of conjugates with macrophages. In spite of increased contacts, macrophages from tumor bearing mice were not cytotoxic. Only preactivated macrophages, by in vivo treatment with Corynebacterium parvum, were shown to be cytotoxic; this function was potentiated when the target cells were opsonized with C3b/iC3b.
Lipari
M
M
Dipartimento Medicina Sperimentale, Università La Sapienza, Rome, Italy.
di Renzo
L
L
Zicari
A
A
Serarcangeli
S
S
Huemer
H P
HP
Larcher
C
C
Dierich
M P
MP
Pontieri
G
G
D000818:Animals; D001665:Binding Sites; D003176:Complement C3 / Q000378:metabolism*; D003170:Complement Pathway, Alternative; D003602:Cytotoxicity, Immunologic; D004912:Erythrocytes / Q000276:immunology; D005260:Female; D008262:Macrophage Activation; D008264:Macrophages / Q000276:immunology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009374:Neoplasms, Experimental / Q000276:immunology*; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism
D003176:Complement C3; D010446:Peptide Fragments