Synthesis of factor D by normal human hepatocytes.
BACKGROUND
Unlike most complement proteins, complement factor D is believed to be synthesized not by the liver but exclusively by adipose tissue.


METHODS
Culture supernatants obtained from primary culture of normal human hepatocytes were assayed for factor D by ELISA and analyzed by Western blotting.


RESULTS
When normal hepatocytes were cultured in protein-free medium without addition of any stimulator for 5 days, factor D was detected in the supernatants at levels as high as 331.07 +/- 41.38 microgram/10(6) cells. Addition of TNF-alpha, IFN-gamma, IL-1beta or LPS to the medium did not result in any distinct effect on the amounts of secreted factor D. Reversible inhibition of factor D secretion by these cells was observed when cultured in the presence of cycloheximide. By immunoblot analysis, secreted factor D exhibited double bands, one with a molecular weight similar to factor D in normal human serum and the other with a slightly larger molecular weight.


CONCLUSIONS
Normal human hepatocytes synthesize factor D constitutively. The liver may be a major source of plasma factor D.
Kitano
E
E
Department of Medical Technology, Osaka Prefectural College of Health Sciences, Osaka, Japan.
Kitamura
H
H
D002478:Cells, Cultured; D011416:Complement Factor D / Q000096:biosynthesis*; D003470:Culture Media; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D015151:Immunoblotting; D008099:Liver / Q000166:cytology* / Q000378:metabolism*
D003470:Culture Media; C493488:CFD protein, human; D011416:Complement Factor D