Expression of H-ficolin/Hakata antigen, mannose-binding lectin-associated serine protease (MASP)-1 and MASP-3 by human glioma cell line T98G.

Mannose-binding lectin (MBL) is a C-type lectin involved in the first line of host defense and it requires MBL-associated serine proteases (MASP) for activation of the lectin complement pathway (LCP). Recently we reported that human ficolins, L-ficolin/P35 and H-ficolin/Hakata antigen, as well as MBL activate the LCP in association with MASP. We investigated in vitro expression of complements of the lectin complement pathway in several cell lines. Out of 17 cell lines tested using RT-PCR, a human glioma cell line, T98G, expressed high levels of H-ficolin/Hakata antigen, MASP1 and MASP3 mRNAs. Similar results were obtained in four other glioma lines. In addition, mRNAs for C1r, C1s, C2, C3, C4, C5 and C6 were also detected in T98G cells, but very low amount of mRNAs for C1q and MBL. MBL mRNA was seen in two of the other glioma cell lines. An ELISA of culture supernatants showed that T98G cells secreted a considerable amount of MASP-1 and MASP-3 proteins. SDS-PAGE and immunoblotting analyses showed the secreted H-ficolin/Hakata antigen, MASP-1 and MASP-3 to be 34, 81 and 105 kDa in size respectively, similar to their serum counterparts. Since the glioma cells used are derived from astrocytes, this suggests that human astrocytes may be a source of some components of the LCP in the brain.