# Xenogeneic Testicular Cell Vaccination Induces Long-Term Anti-Cancer Immunity in Mice

## TL;DR

A xenogeneic testicular cell vaccine from rams can induce long-term anti-cancer immunity in mice, improving survival and reducing tumor growth.

## Contribution

This study demonstrates that xenogeneic testicular cell vaccination can induce cross-reactive, long-lasting anti-cancer immunity in mice.

## Key findings

- Xenogeneic vaccination with ram-derived testicular cells significantly improved survival rates in mice implanted with LLC carcinoma cells.
- Vaccinated mice exhibited increased interferon gamma levels and reduced regulatory T cells in the spleen.
- Immunity from vaccinated mice could be adoptively transferred to naïve animals, enhancing their survival.

## Abstract

Cancer/testis antigen (CTA) gene products are expressed in most malignant tumours, while under normal conditions their expression is primarily restricted to testicular cells. In this study, we investigated the prophylactic application of a xenogeneic (ram-derived) testicular cell (TC) vaccine for cancer prevention in an experimental animal model. C57BL/6 mice were immunised three times with either xenogeneic (ram) or syngeneic (mouse) formaldehyde-fixed spermatogenic tissue-derived cells. Following vaccination, mice were implanted with live B16 melanoma or LLC carcinoma cells. Tumour-bearing mice were subsequently assessed for survival and immunological parameters indicative of anti-cancer immunity. Xenogeneic vaccination with TCs induced cross-reactive immune responses to both B16 melanoma and LLC carcinoma antigens (Ags), as determined by an MTT ((3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Prophylactic vaccination with xenogeneic TCs (xTCs), but not syngeneic TCs (sTCs), significantly improved survival rates, with 30% of vaccinated mice surviving after LLC carcinoma implantation. The induced immunity was long-lasting as mice implanted with LLC carcinoma cells 3–6 months post-vaccination exhibited prolonged survival. Furthermore, lymphoid cells from surviving vaccinated mice were capable of adoptively transferring anti-cancer immunity to naïve animals, significantly increasing their survival rates upon subsequent LLC carcinoma cell implantation. Vaccinated mice bearing LLC tumours exhibited a reduction in regulatory CD4⁺CD25⁺Foxp3⁺ T cells in the spleen, with no effect observed in the central memory CD4⁺CD44⁺CD62L⁺ T-cell compartment. Moreover, vaccinated mice displayed increased interferon gamma (IFN-γ) levels in the blood, with no significant changes in interleukin-10 (IL-10) levels. Prophylactic vaccination with xenogeneic CTAs effectively induces long-term, stable anti-cancer immunity, demonstrating potential for future immunopreventive strategies.