Identification of acute myeloid leukemia patients with diminished expression of CD13 myeloid transcripts by competitive reverse transcription polymerase chain reaction (RT-PCR)

Normal myeloid cells of monocytic and granulocytic origin express the metal lopeptidase cluster of differentiation 13 (CD 13) on the surface just as le ukemic blasts in most acute myeloid leukemias (AML). A minor percentage of AML patients, however, lack the surface expression of CD13 antigen. To stud y this difference in CD13 surface expression, specific CD13 mRNA from 44 in dividuals were quantified by competitive reverse transcription polymerase c hain reaction (RT-PCR). Absolute values for CD13 transcripts were normalise d against glyceraldehyde-3-phosphate dehydrogenase (GAPDH) transcript level s to control for variations in sample preparation and mRNA degradation. By correlating normalised CD13 transcript levels and CD13 surface expression, a subgroup of AML patients was identified, having simultaneous diminished l evels of myeloid CD13 transcripts and surface expression of the correspondi ng antigen. For this subgroup we suggest CD13/aminopeptidase N (APN) gene e xpression to be restricted primarily by limited amounts of transcripts. For the majority of AML patients determinants in addition to transcript levels must be involved in regulating CD13/APN gene expression. (C) 2000 Elsevier Science Ltd. All rights reserved.