Murine monoclonal antibody recognizing a 90-kDa cell-surface determinant selectively lost by multi-drug-resistant variants of CEM cells.
We describe a murine IgG1 monoclonal antibody (MAb56), specific for a cell-surface protein structure (MC56 determinant) expressed by the human CEM cell line. A large band of approximately 90 kDa was identified as the main specific component of the MC56 determinant. Such a 90-kDa protein is significantly associated with the drug-sensitive phenotype, its expression being progressively reduced quantitatively in multi-drug-resistant (MDR) variants of CEM cells, according to the extent of drug resistance. In addition, the MC56 determinant is expressed de novo in drug-sensitive revertant cell lines derived from MDR cells and unreactive with the MAb56. The MAb56 shows a high affinity towards the immunizing drug-sensitive CEM cell line (Ka = 1.86 x 10(9) L/mole) while not binding to MDR cell variants. The expression of the MC56 molecule on a variety of human cells and tissues makes such a cellular determinant a candidate as a marker for studying the MDR phenomenon both in vivo and in vitro.
Laboratorio di Immunologia, Istituto Superiore di Sanità, Rome, Italy.
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M
Cianfriglia
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Cenciarelli
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M
Tombesi
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S
Barca
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M
Mariani
S
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Morrone
A
A
Santoni
P
P
Samoggia
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Alessio
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Malavasi
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000302:isolation & purification; D000918:Antibody Specificity / Q000276:immunology; D000954:Antigens, Surface / Q000032:analysis / Q000276:immunology; D002460:Cell Line / Q000187:drug effects / Q000276:immunology; D004351:Drug Resistance / Q000276:immunology; D000939:Epitopes / Q000032:analysis / Q000276:immunology*; D006801:Humans; D006825:Hybridomas / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology / Q000302:isolation & purification; D051379:Mice; D008970:Molecular Weight; D010641:Phenotype; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000276:immunology*; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000276:immunology
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D000939:Epitopes; D007074:Immunoglobulin G