Tumor Infiltrating Lymphocytes in Pet Rabbit Mammary Carcinomas: A Study with Relevance to Comparative Pathology
Targos Molecular Pathology GmbH, Germaniastrasse 7, 34119 Kassel, Germany
Institute of Veterinary Pathology, University of Leipzig, An den Tierkliniken, 04109 Leipzig, Germany
Institute of Anatomy, Experimental Neurobiology, Goethe-University, Theodor-Stern-Kai 7, 60590 Frankfurt/Main, Germany
Laboklin GmbH & Co. KG, Steubenstrasse 4, 97688 Bad Kissingen, Germany
Author to whom correspondence should be addressed.
Received: 16 July 2020
Revised: 12 August 2020
Accepted: 13 August 2020
Published: 17 August 2020
The interaction between tumors and immune cells influences tumor fate, i.e., regression, growth, or even metastases. The evaluation of tumor infiltrating lymphocytes (TILs) in human breast cancer has prognostic value. Pet rabbits develop spontaneous mammary carcinomas and have an immune system that is comparable with that of humans, so that they have the potential to provide an animal model for human breast cancer. To further substantiate this similarity, this study examined TILs in 107 pet rabbit mammary carcinomas according to criteria established for human breast cancer. For TIL evaluation routinely stained microscopic sections were examined by light microscopy. Relevant histological and immunohistochemical tumor characteristics were obtained from a data base. Results showed that increased presence of stromal TILs was statistically associated with histological tumor features indicative of a less aggressive biological behavior, i.e., reduced tumor cell proliferation and a lower histological grade. The expression by tumor cells of calponin, a presumed tumor suppressor protein, was also associated with their reduced proliferation and a higher percentage of stromal TILs. Data suggest that higher percentages of stromal TILs may have the potential to serve as favorable prognostic indicator in rabbit mammary carcinomas and support the value of pet rabbits for comparative research.