IL-17 promotes myeloma cell growth in vitro and in vivo. (A) Myeloma cell lines (N = 7) were incubated with or without IL-17 and proliferation was measured by 3H-thymidine incorporation after 3 days. Data are presented as percentage increase in proliferation in presence of IL-17 compared with control and showed as mean plus or minus SEM. (B) Myeloma cell lines (OPM-1 and U266) were cultured in methocult agar plates in the presence or absence of IL-17. Representative photomicrograph is presented. Photographs were obtained using a Nikon TE200 microscope (40× objective) with attached camera (Nikon) at room temperature (total magnification 200×) and analyzed with Metafluor software (Molecular Devices). (C) Primary MM cells (N = 3) were cultured in methocult agar plates in the presence or absence of IL-17 and number of colonies was counted in unit area and presented as mean plus or minus SEM. (D) MM cell lines were cultured with or without BMSCs in the presence or absence of IL-17 and proliferation was increased as measured by 3H-thymidine incorporation after 3 days and presented as percentage of proliferation of control. (E) Serum-starved MM cells were labeled with calcein, washed, and added to BMSC-coated plates for 4 hours and nonadherent cells were removed by washing. Adhesion was measured by measuring the absorbance using 492/520 nm filter set with a fluorescence plate reader. Results represent mean plus or minus SEM of 4 independent experiments performed in triplicate. (F) Myeloma cells suspended in medium with or without IL-17 were injected subcutaneously in SCID mice (3 mice per group), and tumor size was measured after 3 weeks after MM cell injection. *P < .05.
