Exceptional Resistance of Human H2 Glioblastoma Cells to Complement-Mediated Killing by Expression and Utilization of Factor H and Factor H-Like Protein 1

Abstract

Of over 20 nucleated cell lines we have examined to date, human H2 glioblastoma cells have turned out to be the most resistant to complement-mediated cytolysis in vitro. H2 cells expressed strongly the membrane attack complex inhibitor protectin (CD59), moderately CD46 (membrane cofactor protein) and CD55 (decay-accelerating factor), but no CD35 (complement receptor 1). When treated with a polyclonal anti-H2 Ab, anti-CD59 mAb, and normal human serum, only 5% of H2 cells became killed. Under the same conditions, 70% of endothelial-like EA.hy 926 cells and 40% of U251 control glioma cells were killed. A combined neutralization of CD46, CD55, and CD59 increased H2 lysis only minimally, demonstrating that these complement regulators are not enough to account for the resistance of H2 cells. After treatment with Abs and serum, less C5b-9 was deposited on H2 than on U251 and EA.hy 926 cell lines. A reason for the exceptional resistance of H2 cells was revealed when RT-PCR and protein biochemical methods showed that the H2 cells, unlike the other cell lines tested, actively produced the soluble complement inhibitors factor H and factor H-like protein 1. H2 cells were also capable of binding human factor H from the fluid phase to their cell surface and promoted the cleavage of C3b to its inactive form iC3b more efficiently than U251 and EA.hy 926 cells. In accordance, anti-factor H mAbs enhanced killing of H2 glioblastoma cells. Taken together, our results show that production and binding of factor H and factor H-like protein 1 is a novel mechanism that these malignant cells utilize to escape complement-mediated killing.

Regulation of complement and modulation of its activity in monoclonal antibody therapy of cancer

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Discovery and Verification of Osteopontin and Beta-2-microglobulin as Promising Markers for Staging Human African Trypanosomiasis

“…Trypanosomes are able to activate the alternative complement pathway in blood (35), whereas decreased complement activation was reported during the 1980s in infective cultures of T. cruzi, responsible for Chagas' disease (36). Complement factor H is the principal inhibitor of the alternative pathway, and is also involved in the protection of epithelial, endothelial, and some cancer cells against complement action (37). In our population of T. b. gambiense patients, overexpression of CFH during the second stage of disease was only confirmed with ELISA.…”

Identification and analysis of tumour-associated antigens in hepatocellular carcinoma

“…Sequencing analysis showed that the 52 clones represented 30 distinct antigens (Table 1). Of these 30 antigens, one is the CT antigen CAGE protein, and the other 13 antigens, which had previously been reported to be involved in tumorigenesis or suspected to be involved in tumour progression, including CDC37 (Stepanova et al, 2000), MIF (Li et al, 2004), galectin 4 (Huflejt and Leffler, 2004), galectin 8 (Bidon-Wagner and Le Pennec, 2004), PINCH (WangRodriguez et al, 2002), SPRY2 (Lee et al, 2004a), HSPCA (Becker et al, 2004;Huang et al, 2004b), transgelin 2 (Shields et al, 2002), HDAC2 , H factor (Junnikkala et al, 2000), AAT (Huang et al, 2004a), B factor (Perou et al, 1999), PIBF (Lachmann et al, 2004). Three other antigens (SR140 protein, SFRS2IP, RNPC2) may be involved in the regulation of alternative mRNA splicing, PSMA7 is related to hepatitis B and hepatitis C viral replication (Zhang et al, 2000;Kruger et al, 2001), and the remaining 12 antigens have no known association with cancer or hepatitis B or hepatitis C.…”