Glutathione-S-transferase activity and multidrug resistance phenotype in chronic lymphocytic leukemia: do they have any clinical relevance?

Abstract

BACKGROUND. Lymphocytes from patients affected by B-cell chronic lymphocytic leukemia (B-CLL) have frequently been shown to be positive for the multidrug resistance (MDR) phenotype. However, this phenotype does not seem to be responsible for the resistance to alkylating agents usually employed in the management of CLL. METHODS. Lymphocytes from 42 patients were evaluated by flow cytometry for P-170 expression and by spectrophotometry for glutathione-S-transferase (GST) activity. RESULTS. Our findings show that GST is not related to any clinical parameter but is increased in treated patients. Conversely, 85% of patients were positive for P-170 and this was related to the percentage of CD5/CD19-positive lymphocytes. CD5/CD19-negative patients were also negative for P-170. MDR was not related to any clinical parameter evaluated nor to GST activity in lymphocytes. CONCLUSIONS. MDR is constitutively expressed in B-cell chronic lymphocytic leukemia and seems to be related to a CD5/CD19 B-CLL phenotype. The increase of GST activity in treated patients is statistically significant (p < 0.005).