TUMOR-INFILTRATING LYMPHOCYTES AND P-GLYCOPROTEIN/MELANOMA ANTIGEN A EXPRESSION IN VINCRISTINE-TREATED CANINE TRANSMISSIBLE VENEREAL TUMORS

Abstract

In this study, canine transmissible venereal tumors (CTVTs) were evaluated for tumor-infiltrating lymphocytes, MHC class II antigen expression, melanoma antigen A (MAGE-A protein), and P-glycoprotein (P-gp). Vincristine (VCR)-sensitive CTVTs (VSCTVTs) were evaluated before and after VCR treatment. Immunohistochemical analysis was performed to evaluate the numbers of CD3[Formula: see text] lymphocytes, CD79a[Formula: see text] lymphocytes, and MHC II[Formula: see text] CTVT cells. Expression levels of P-gp, MAGE-A, and MHC class II antigen were evaluated. The numbers of CD3[Formula: see text] lymphocytes, CD79a[Formula: see text] lymphocytes, and MHC II[Formula: see text] CTVT cells were significantly elevated ([Formula: see text]). After VCR treatment, 100% (8/8) of VSCTVTs exhibited significantly higher MAGE-A expression in CTVT cells, compared with 74% (20/27) of VSCTVTs before VCR treatment. Strong expression of P-gp was found in 14.2% (1/7) of VSCTVTs after VCR treatment compared with VSCTVTs before treatment (83.3%, 5/6). These results demonstrated that regression of VSCTVTs following VCR treatment was associated with an obvious increase in the proportion of MHC class II[Formula: see text] CTVT cells and a significant increase in infiltration by T (CD3[Formula: see text] and B (CD79a[Formula: see text] lymphocytes, as well as decreased expression of P-gp and increased expression of MAGE-A in CTVT cells.