Intra-bone marrow injection of dendritic cells for treatment of malignant tumor in mice.

It has recently been reported that antigen presentation from dendritic cells (DCs) to T cells occurs in the bone marrow, and that not only tumor antigen-pulsed DCs but also unpulsed DCs have some anti-tumor effects, resulting from the induction of anti-tumor immunity. In this paper, we examined whether dendritic cells induced from bone marrow cells (BMCs) have the capacity to suppress tumor growth and, if so, which route (intravenous, subcutaneous, or intra-bone marrow injection) is best. BALB/c mice that had been subcutaneously inoculated with Meth A (a murine fibrosarcoma cell line) were injected with BMC-derived DCs via the above three routes. We also examined the tumor suppressive effects of DCs from tumor-bearing mice. Although IBM injection showed similar effects to subcutaneous injection on the suppression of tumor growth, intravenous injection was less effective. It seems likely that the IBM injection of DCs activates tumor-specific T cells, resulting in the suppression of the tumor growth. DCs derived from tumor-bearing mice had some effects on the suppression of tumor growth but they were less effective than DCs from untreated mice.