文摘
Melanoma is an aggressive skin cancer, however it is immunogenic. The size of the primary tumor is associated with the nodal metastases. Our goals were to characterize melanoma-associated antigens (MAAs) and tumor-infiltrating T-lymphocytes (TILs) subsets in the few very large tumors (VLTs) developing in ret transgenic mice of melanoma. Tumors >700 mg (VLTs) were investigated for MAAs and subsets of TILs. Immunohistochemistry and flow cytometry-based studies were performed to determine the infiltration patterns of T-lymphocytes in VLTs. It was observed that zinc fixative restores the antigenicity of the cell-surface markers of lymphocyte subpopulations without the need of antigen retrieval, whereas formalin-based fixative fails to restore the antigenicity in the presence of antigen retrieval in the immunohistochemistry. VLTs from ret mice express MAAs, such as Tyrosinase, TRP-1, TRP-2 and gp-100. The mean ± standard deviation (S.D.) T-cell infiltration per 400 times-high power field in VLTs; CD4+ (2.33 ± 1.3), CD8+ (2.00 ± 1.0), and CD4+ Foxp3+ (2.5 ± 0.5) regulatory T cells infiltration was exclusively restricted to the tumor stroma. Moreover, our flow cytometry-based data reveal that % mean ± S.D. naive CD3+ CD4+ T cell infiltration (32.8 ± 4.0%) was significantly larger than effector (25.8 ± 2.8%, p < 0.01) and central memory cells (16.1 ± 3.7%, p < 0.001) in VLTs. Similarly, between CD3+ CD8+ T cells, naive cells infiltrate (57.7 ± 2.3%) in a significantly larger frequency than effector (5.0 ± 0.4%, p < 0.0001) and central memory cell (4.8 ± 1.7%, p < 0.0001) subsets. These results suggest that the VLTs from ret mice display lowered infiltration ratios between memory and naive T cells, which could be associated with the relatively large growth of VLTs.
