Toxoplasma gondii (T. gondii) is prevalent intracellular parasite and a cause of worldwide infection in the human population. An inhibitory effect of this parasite on cancer growth has been demonstrated in cell culture and animal models. To determine whether the anticancer activities of T. gondii are associated with host immune response, in the current study the reactivity of anti-T. gondii antiserum with the surface of cancer cell lines was investigated. Anti-T. gondii antibodies were raised in rabbit and the reaction of this antiserum in comparison with other anti-parasite antisera (anti-T. vaginalis, anti-hydatid cyst fluid, anti-protoscolices antigens) with mouse melanoma or breast cancer cells lines was investigated using flow cytometry. Anti-T. gondii antiserum reacted markedly with the surface of mouse melanoma and breast cancer cells, and less so with the normal mouse spleen lymphocytes. Meanwhile, the other anti-parasite antisera did not react strongly with the surface of cancer cells compared with normal mouse spleen lymphocytes. In summary, it has been demonstrated herein that anti-T. gondii antiserum may selectively react with the surface of mouse cancer cells but not with normal mouse spleen lymphocytes. Therefore, further study on anti-Toxoplasma antibodies may be useful for directing the application of selective drug delivery in cancer treatment.

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