Lymphadenectomy exacerbates tumor growth while lymphadenectomy plus the adoptive transfer of autologous cytotoxic cells and low-dose cyclophosphamide induces regression of an established murine fibrosarcoma

Abstract

Tumor-draining lymph node (TDLN) ablation is routinely performed in the management of cancer; nevertheless, its usefulness is at present a matter of debate. TDLN are central sites where T cell priming to tumor antigens and onset of the antitumor immune response occur. However, tumor-induced immunosuppression has been demonstrated at TDLN, leading to downregulation of antitumor reaction and tolerance induction. Tolerance in turn is a main impairment for immunotherapy trials. We used a murine immunogenic fibrosarcoma that evolves to a tolerogenic state, to study the cellular and molecular mechanisms underlying tolerance induction at the level of TDLN and to design an appropriate immunotherapy. We determined that following a transient activation, the established tumor induces signs of immunosuppression at TDLN that coexist with local and systemic evidences of antitumor response. Therefore, we evaluated the feasibility of removing TDLN in order to eliminate a focus of immunosuppression and favor tumor rejection; but instead, a marked exacerbation of tumor growth was induced. Combining TDLN ablation with the in vivo depletion of regulatory cells by low-dose cyclophosphamide and the restoring of the TDLN-derived cells into the donor mouse by adoptive transference, resulted in lowered tumor growth, enhanced survival and a considerable degree of tumor regression. Our results demonstrate that important antitumor elements can be eliminated by lymphadenectomy and proved that the concurrent administration of low-dose chemotherapy along with the reinoculation of autologous cytotoxic cells provides protection. We suggest that this protocol may be useful, especially in the cases where lymphadenectomy is mandatory.

B cells inhibit the antitumor immunity against an established murine fibrosarcoma

“…Lymph node draining the tumor site is the first place where the immune response against tumor development takes place. A previous study showed that the initial growth of MCC could induce the activation of TDLN dendritic and T cells (immunogenic phase) (20). As the tumor increased in size, the signs of immune activation at TDLN disappeared as the mice became tolerant (tolerogenic phase) (20).…”

“…Previous studies have described that a progressive increase in IL-10-expressing B cells occurs at the TDLN, as a tumor grows and evolves from an immunogenic to a tolerogenic state (20,22). In order to analyze a possible role for B cells in the establishment of tolerance and consequent tumor progression, TBM were depleted of B cells using an anti-CD20 monoclonal antibody, 3 days prior to or 9 days p.i.…”

“…Later, in the tolerogenic stage, CI is no longer detected and a second tumor implant grows without being rejected (18). MCC growth was also found to induce a series of alterations in the cell composition of tumor-draining lymph nodes (TDLN), including the progressive increase in B cells with the emergence of an IL-10-producing subpopulation (20,22). These results suggest that B cells may be implicated in the downregulation of the antitumor immunity and the establishment of tumor tolerance in the MCC model.…”

“…Methylcolanthrene-induced murine fibrosarcoma (MCC) is a highly immunogenic tumor that elicits an early specific antitumor immune reaction, which is not strong enough to impede tumor growth (18)(19)(20)(21). The antitumor response declines at a certain tumor volume (~500 mm 3 ) and disappears comprising a state of tolerance (18)(19)(20)(21). Immunological characteristics of MCC and its rapid growth in vivo make it a suitable model to study mechanisms underlying tumor immunity and tumor-induced immunosuppression.…”

“…Evidence that accounts for the role of B cells in tumor-induced immunosuppression includes the existence of human B cells with a regulatory phenotype in solid tumors (11), the B cell-mediated induction of Tregs expansion (12)(13)(14) and the increase of tumor growth (12,(15)(16)(17). Methylcolanthrene-induced murine fibrosarcoma (MCC) is a highly immunogenic tumor that elicits an early specific antitumor immune reaction, which is not strong enough to impede tumor growth (18)(19)(20)(21). The antitumor response declines at a certain tumor volume (~500 mm 3 ) and disappears comprising a state of tolerance (18)(19)(20)(21).…”