Secretion of soluble complement inhibitors factor H and factor H-like protein (FHL-1) by ovarian tumour cells.
Bottom Line: We observed that the soluble complement regulators factor H and factor H-like protein were abundantly present in ascites samples as well as in primary tumours of patients with ovarian cancer.In ascites samples the mean level of factor H-like protein (130+/-55 microg ml(-1)) was 5.5-fold higher than in normal human serum (24+/-3 microg ml(-1)).Subsequently, the PA-1 and SW626 cell lines were found to secrete a soluble form of the membrane cofactor protein (CD46).
Affiliation: Department of Bacteriology and Immunology, Haartman Institute, University Central Hospital, FIN-0014 Helsinki, Finland.Show MeSH
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Mentions: Since SK-OV-3 and Caov-3 cells were found to produce and secrete both factor H and FHL-1 into their growth supernatants we wanted to study whether they were capable of promoting the degradation of C3b to iC3b, i.e. whether the secreted proteins acted as cofactors for factor I. Cofactor activity analysis demonstrated that the supernatants of all the cell lines, including those of PA-1 and SW626, promoted factor I-mediated cleavage of 125I-labelled C3b (Figure 5Figure 5
Affiliation: Department of Bacteriology and Immunology, Haartman Institute, University Central Hospital, FIN-0014 Helsinki, Finland.