Intradermal injection, as opposed to subcutaneous injection, enhances immunogenicity and suppresses tumorigenicity of tumor cells.

Tumor cell immunogenicity depends heavily upon the microenvironment in which the cells grow. We have compared the tumorigenicity and immunogenicity of the same tumor cells when injected either into the dermis, a tissue containing numerous dendritic cells (DCs), or s.c., at a site which contains only few DCs. After s.c. injection, progressive tumors were constantly obtained, whereas most intradermal injections did not give rise to tumor and immunized animals against additional challenge. We present evidence that the high density of DCs at dermal sites facilitates the capture of tumor antigens and that local inflammation induces maturation of the DCs and their migration into draining lymph nodes.