Initial steps in lymph node metastasis formation in an experimental system: possible involvement of recognition by macrophage C-type lectins

We used histological observations and experiments with fluorescent cell tra cers to investigate the roles of tissue macrophages in recognition through a galactose/N-acetylgalactosamine-specific C-type lectin (mMGL) in lymph no de metastasis formation by mouse ovarian tumor OV2944-HM-1 (HM-1) cells. Ly mph node metastasis from subcutaneous sites was shown to be initiated by th e entry of tumor cells into the subcapsular sinus of lymph nodes where mMGL -positive cells were mainly located. To investigate whether mMGL-positive c ells contributed to host resistance against lymph node metastasis, we repea tedly treated mice bearing transplanted tumors with an mMGL-blocking monocl onal antibody that was known to inhibit mMGL binding to its ligands. The nu mber of HM-1 cells recovered from lymph nodes 2 weeks after subcutaneous in jections was significantly greater when the mice were treated with the bloc king anti-mMGL antibody. These results suggested that mMGL-positive macroph ages contributed to the host's defense against lymph node metastasis.