Lack of Effect of Different Cytokines on Expression of Membrane-Bound Regulators of Complement Activity on Human Uveal Melanoma Cells

Tumor cells are protected from antibody-dependent complement-mediated lysis by membrane-bound regulators of complement activation (m-RCA). m-RCA are expressed on uveal melanoma cells. We determined whether cytokine treatment affects expression of m-RCA on these cells in vitro. m-RCA expression on uveal melanoma cell lines was studied by flow cytometry, using monoclonal antibodies directed against CD46, CD55, and CD59. Cytokines studied were interferon-α (IFN-α), IFN-γ, interleukin-lB (IL-1B), IL-12, and tumor necrosis factor-α (TNF-α). All three m-RCA were expressed on the uveal melanoma cell lines (CD59>>CD46>CD55), although in variable amounts. With a few exceptions, the cytokines had no effect on m-RCA expression. CD55 expression was not influenced by any of the cytokines. IFN-α downregulated expression of CD46 on one cell line (p < 0.01). TNF-α upregulated CD59 expression on two of the five cell lines (p < 0.012 and p < 0.001, respectively), which effect was dose dependent. IFN-α, IFN-γ, IL1-β, IL12, and TNF-α had limited effects on m-RCA expression on uveal melanoma cells in vitro.