ALDH+/CD44+/CD24− expression in cells from body cavity fluids

Abstract

Enhanced expression of aldehyde dehydrogenase 1 (ALDH1) and phenotypic markers (CD44(+)/CD24(-)) in stem cells from breast tumors has been reported. This study was undertaken to monitor expression of these markers in cells from body cavity fluids of female patients suspected to have a malignancy. Cells from peritoneal and pleural fluids of 100 female patients were examined by diagnostic cytology and analyzed by laser flow cytometry for enhanced ALDH1 expression. Cells from 36 body cavity fluids with ALDH1(bright) fluorescence were then analyzed for the expression of CD44 and CD24 markers. In samples positive for malignancy, ALDH1(bright) cells with both SSC(low) and SSC(high) were seen. In 15 body cavity fluids positive for malignancy, the percentage of ALDH1(bright) cells ranged from 0.26 to 6.34% of the total cells. The percentage of ALDH1(bright) cells with CD44(+)/CD24(-) expression in these samples ranged from 0.02 to 3.66%. ALDH1(bright) cells with CD44(+)/CD24(-) expression were also present in body cavity fluids of patients in whom diagnostic cytology could not detect any malignancy. However, the percentage of ALDH1(bright) and CD44(+)/CD24(-) cells amongst the 21 body cavity fluids with negative cytology was lower than that of samples with malignancy. Expression of ALDH1(bright) and the CD44(+)/CD24(-) phenotype in body cavity fluids in which diagnostic cytology could not find any malignant cells suggests that this phenotype may not be restricted to the putative breast tumor stem cells. It is possible that only subsets of cells with this phenotype are the putative breast tumor stem cells.