Detection of multidrug-resistant protein, P-glycoprotein in childhood leukaemia and lymphoma.

Flow cytometric detection of surface P-glycoprotein, a multidrug-resistant gene product, with a monoclonal antibody, MRK 16, was performed on cells obtained from 18 children with leukaemia and lymphoma. Of 18 patients examined, 1 with malignant lymphoma at relapse showed a significant increase in P-glycoprotein-positive cells and a strong resistance to chemotherapy. Overexpression of P-glycoprotein in a case with B-cell type malignant lymphoma was confirmed by immuno-precipitation and Northern hybridization analysis. The present study suggests that an increased expression of surface P-glycoprotein might be involved in multidrug resistance at least in a certain case of childhood leukaemia and lymphoma.