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Updated: Aug 8, 2026
Evaluation of Tumor-infiltrating Leukocyte Subsets in a Subcutaneous Tumor Model
Published on: April 13, 2015
Immunohistochemical characterization of the leucocytic infiltrate associated with canine seminomas
V Grieco1, M Rondena, S Romussi
1Dipartimento di Patologia Animale, Igiene e Sanità Pubblica Veterinaria, Sezione di Anatomia Patologica Veterinaria e Patologia Aviare, Facolta di Medicina veterinaria, Via Celoria 10, 20133 Milano, Italy.
Insights
Canine seminomas feature immune cell infiltration, primarily CD8+ T lymphocytes. These cells, along with neoplastic cells expressing MHC I, suggest a cytotoxic reaction contributing to favorable prognoses in canine seminomas.
Area of Science:
- Veterinary Pathology
- Immunology
- Oncology
Background:
- Leukocytic infiltration is common in canine and human seminomas, but its role is unclear.
- Understanding the immune microenvironment is crucial for canine seminoma prognosis.
Purpose of the Study:
- To characterize the infiltrating leukocytes in canine seminomas.
- To investigate the immune response within canine seminoma tumors.
Main Methods:
- Immunohistochemical analysis of 10 canine seminoma samples.
- Use of monoclonal antibodies against various leukocyte markers (CD18, CD11a, CD11b, CD11c, CD21, CD3, CD4, CD8) and MHC I/II.
Main Results:
- Infiltrating leukocytes were mainly CD3+ T lymphocytes, particularly the CD8+ subset, and CD21+ B lymphocytes.
- CD11c+ cells (macrophages/APCs) were more numerous than CD11b+ cells (monocytes/granulocytes).
- Both infiltrating and neoplastic cells expressed MHC I and MHC II, with neoplastic cells predominantly expressing MHC I.
Conclusions:
- The presence of CD8+ lymphocytes and MHC I expression suggests a cell-mediated cytotoxic reaction against canine seminoma cells.
- This immune response may explain the generally favorable prognosis observed in canine seminomas.
Abstract:
Both canine and human seminomas are typically associated with leucocytic infiltration, the role of which remains poorly understood. In this study, leucocytes infiltrating 10 canine seminomas were characterized. Monoclonal antibodies directed against CD18, CD11a, CD11b, CD11c, CD21, CD3, CD4, CD8 and Major Histocompatibility Complex class I and II (MHC I and MHC II) were also employed. Infiltrating leucocytes were located around vessels, adjacent to the thin fibrous septa between neoplastic lobules, and were also scattered singly amongst neoplastic cells. The more profuse infiltrates often had the appearance of follicular aggregates. Immunohistochemically, all the samples showed generally similar results. Most of the infiltrating cells were positive for CD18 and CD11a. Infiltrating cells were mainly T lymphocytes (CD3+), particularly of the CD8+ subset. B lymphocytes (CD21+) were detectable in almost all infiltrates; in the follicular aggregates they were centrally located, whereas T lymphocytes (CD3+) lined the periphery. CD11c+ cells were always more numerous than CD11b+ cells, demonstrating that if macrophages and antigen-presenting cells (APCs) were well represented, monocytes and granulocytes were practically absent. Almost all of the infiltrating cells were positive for both MHC I and MHC II antigens and, in nine samples, a large number of neoplastic cells expressing MHC I were detected. A few neoplastic cells expressing MHC II were observed in seven cases. The presence of CD8+ lymphocytes, together with the large number of both infiltrating and neoplastic cells expressing MHC I, suggests that the lymphocytes mediate a cytotoxic reaction against the neoplastic cells. This hypothesis may underlie the favourable prognosis frequently associated with canine seminomas.
