Tumor site-selective localization of an adoptively transferred T cell line expressing a macrophage lectin

CTLL-2 cells were transfected with an expression vector that contained cDNA of a mouse macrophage galactose/N-acetylgalactosamine-specific calcium-type lectin (MMGL) and a stable transfectant (CTL-ML) was established. These cells and mock transfectant cells (CTL-CEP) were labeled with a long-term fluorescent cell tracer, DiI. The labeled cells were intravenously injected into mice that contained established lung metastases produced by OV2944-HM-1 ovarian tumor cells. Analyses with fluorescence microscopy of a series of frozen lung sections from the recipient mice revealed that CTL-ML preferentially accumulated in the lung metastatic nodules, whereas CTL-CEP did not. Time course studies showed that the preferential accumulation was evident 3 days after adoptive transfer. We also found that OV2944-HM-1 cells bound peanut agglutinin and Vicia villosa agglutinin B4, whose sugar specificity overlaps with the specificity of MMGL. These results suggested that MMGL molecules expressed on CTLL-2 cells contributed to their selective trafficking or retention in tumor foci possibly through recognition of tumor-associated cell surface carbohydrate antigens. These results also suggested that MMGL could be used for the selective targeting of effector cells in adoptive immunotherapy.