Quantification of intrinsic MDR-1 gene expression in different immunophenotypes of canine multicentric lymphomas.

Little is known about the intrinsic expression of the multidrug resistance gene type 1 (MDR-1) in dogs with multicentric lymphoma of different immunophenotypes assessed by qRT-PCR. The purpose of this study is to evaluate the level of MDR-1 expression by real-time PCR on biopsy samples from enlarged lymph nodes of 29 untreated dogs with different immunophenotypes of multicentric lymphoma (B-cell vs CD45+ T-cell vs CD45- T-cell). Cell lineage was established by flow cytometry based on the expression of CD3, CD4, CD5, CD8, CD21, and CD45. Our results indicate that MDR-1 gene expression is detectable in nearly 80 % of newly diagnosed canine lymphomas of different immunophenotypes. MDR-1 expression was undetectable in 5/13 of B-cell lymphomas and 1/10 of CD45+ T-cell lymphomas, while all CD45- T-cell lymphomas were quantifiable. By analyzing the level of MDR-1 gene expression in quantifiable samples, the expression of MDR-1 in dogs with CD45- T-cell lymphoma was higher than observed in B and CD45+ T-cell lymphomas, suggesting that the lymphoma immunophenotype is an important factor that influences the expression levels of the MDR-1 gene.