Absence of induction of IL-1 production in human monocytes by complement fragments.
The ability of C fragments to induce IL-1 production in human monocytes was examined by using various approaches to carefully exclude the role of contaminating endotoxin. The presence of IL-1 activity in monocyte supernatants and lysates was assayed by the augmentation of PHA-induced proliferation of murine thymocytes. SRBC were opsonized with IgM rabbit antibodies and various human C components to prepare EAC reagents that contained less than 25 pg LPS/ml of EAC at 5 x 10(8) cells/ml. EAC1q, EAC4b, EAC4b2aoxy, EAC4b2aoxy C3b, EAC4b2aoxyC3bi, and EAC4b2aoxyC3d all failed to induce IL-1 production when incubated at 10- to 100-fold excess with adherent human monocytes. Similarly, LPS-free purified C3a, C5a, and C5a des Arg all showed no IL-1-inducing activities at concentrations up to 25 micrograms/ml. However, the same C5a preparations were active on human monocytes in the induction of chemotaxis, and C3a and C5a both induced skin-blueing in guinea pigs. Fragment Ba and Bb preparations purified by gel filtration chromatography contained approximately 100 pg LPS/micrograms Ba or Bb. These Ba and Bb preparations at 10 and 50 micrograms/ml, respectively, induced IL-1 production in the presence of 5 micrograms/ml polymyxin B (PMB). However, Ba and Bb preparations purified by affinity chromatography and HPLC contained lower levels of endotoxin contamination and displayed IL-1-inducing activities at Ba and Bb concentrations of 50 and 100 micrograms/ml, respectively, that were almost completely inhibited by PMB. To explore further the role of contaminating endotoxin, a Bb preparation was adsorbed with PMB-4B in the presence of a dialyzable detergent to remove LPS bound to the Bb. This LPS-free Bb preparation failed to induce IL-1 production while maintaining intact enzymatic activities. These results indicate that various solid phase or soluble C fragments, including C3b, iC3b, C3d, C3a, C5a, Ba or Bb do not induce IL-1 production in human monocytes in the absence of contaminating endotoxin.
Department of Medicine, University of Colorado Health Sciences Center, Denver 80262.
W P
WP
Arend
R J
RJ
Massoni
M A
MA
Niemann
P C
PC
Giclas
D000936:Antigen-Antibody Complex / Q000502:physiology; D003166:Complement Activating Enzymes / Q000502:physiology; D003172:Complement C1 / Q000502:physiology; D015922:Complement C1q; D003176:Complement C3 / Q000502:physiology; D015926:Complement C3a; D003179:Complement C3b / Q000502:physiology; D015933:Complement C3d; D003181:Complement C4 / Q000502:physiology; D015935:Complement C4b; D003182:Complement C5 / Q000502:physiology; D015936:Complement C5a; D011415:Complement Factor B / Q000502:physiology; D003165:Complement System Proteins / Q000502:physiology*; D006801:Humans; D007375:Interleukin-1 / Q000096:biosynthesis*; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism*; D010446:Peptide Fragments / Q000502:physiology*
D000936:Antigen-Antibody Complex; D003172:Complement C1; D003176:Complement C3; D003181:Complement C4; D003182:Complement C5; D007375:Interleukin-1; D010446:Peptide Fragments; D015922:Complement C1q; D015926:Complement C3a; D003179:Complement C3b; D015933:Complement C3d; D015935:Complement C4b; D015936:Complement C5a; D003165:Complement System Proteins; D003166:Complement Activating Enzymes; D011415:Complement Factor B