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Expression of the multiple drug resistance gene (mdr‐1) and epitope masking in chronic lymphatic leukaemia
Author(s) -
Cumber Peter M.,
Jacobs Allan,
Hoy Terry,
Fisher Janet,
Whittaker John A.,
Tsuruo Takashi,
Padua Rose Ann
Publication year - 1990
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1990.tb07876.x
Subject(s) - epitope , monoclonal antibody , p glycoprotein , chronic lymphocytic leukemia , multiple drug resistance , flow cytometry , lymphatic system , immunofluorescence , immunology , cytotoxic t cell , medicine , drug resistance , biology , cancer research , microbiology and biotechnology , antibody , leukemia , in vitro , biochemistry
S ummary Resistance to cytotoxic agents is a common clinical problem in the treatment of chronic lymphatic leukaemia (CLL). The multidrug resistant (MDR) phenotype characterized by increased levels of a specific cell membrane p‐glycoprotein. confers cross resistance to a wide range of structurally dissimilar antineoplastic drugs. We have studied the expression of this p‐glycoprotein in chronic lymphatic leukaemia measured by immunofluorescence using a monoclonal antibody MRK 16 by flow cytometry. Initial results showed that only 12% of lymphocyte samples from CLL patients showed increased p‐glycoprotein, conflicting with a previous observation that 53% of CLL patients had an increased level of mdr‐1 mRNA. Treatment of the cells with neuraminidase to remove sialic acid residues increased the proportion of patients showing increased p‐glycoprotein to 52%. This suggests that in a subset of CLL patients post translational modification of the protein occurs masking the epitope recognized by MRK 16. Abnormal sialylation patterns associated with malignancy are a well‐recognized phenomenon.