Fingolimod blocks antitumor immunity and prevents rejection of myeloma and B-cell lymphoma in TCR-transgenic SCID mice. (A) Id-specific TCR-transgenic (TCR-tg) SCID mice were inoculated subcutaneously with 1.6 × 105 MOPC315 myeloma cells and treated daily with either fingolimod (FTY720, Selleck Chemicals; 2 μg/g bodyweight) or with vehicle only (0.8% DMSO; Sigma-Aldrich) delivered intraperitoneally. Tumor growth was followed by palpation. Mice were euthanized when the tumor reached 10 mm in diameter (n = 14-17). (B) Id-specific TCR-transgenic SCID mice were inoculated subcutaneously with 1.6 × 105 F9 B-lymphoma cells and treated daily with fingolimod or with vehicle only. F9 cells are A20 B-lymphoma cells transfected with Id-containing L-chain from MOPC3157 (n = 14-16). (C) Nontransgenic SCID mice were inoculated subcutaneously with 1.6 × 105 MOPC315 cells and treated daily with fingolimod or with vehicle only (n = 8). (D-F) Id-specific TCR-transgenic and nontransgenic SCID mice were inoculated subcutaneously with 105 MOPC315 myeloma cells embedded in Matrigel.9 TCR-transgenic SCID mice were treated daily with fingolimod (1 μg/g bodyweight) or with vehicle only (n = 8-10). SCID mice were left untreated (n = 2). At day +8, draining lymph nodes and Matrigel plugs were dissected and analyzed by flow cytometry.9 (D) CD69 expression on gated Id-specific CD4+ T cells in draining lymph nodes of representative TCR-transgenic SCID mice treated with vehicle only (top) or fingolimod (bottom). Dotted lines indicate an isotype-matched control antibody. (E) Number of Id-specific T cells per Matrigel plug (mean ± SEM). (F) Expression of the activation marker MHC class II on Matrigel-infiltrating CD11b+ macrophages (geometric mean ± SEM). P values were calculated with the log-rank test (A-C) and the t test (E-F). ns indicates not significant.
