Failure of anticytokeratin 18 antibody to improve flow cytometric detection of bladder cancer.
Bladder washing specimens containing inflammatory or squamous cells have been difficult to accurately analyze with single-parameter DNA flow cytometric (FCM) methods. The anticytokeratin 18 antibody, CK5, was used in a multiparameter assay of 275 bladder washing and voided urine specimens to immunoselect only the bladder transitional cells for DNA analysis. Flow cytometric detection of transitional cell carcinoma was increased by immunoselection of CK5-positive cells in specimens from patients with disease. Unfortunately, a similar increase in hyperdiploid cells in pathologically benign specimens was observed, which resulted in a false-positive rate of 45%. In some instances, multiparameter FCM assays with CK5 could detect aneuploid cell populations not clearly evident by single-parameter analysis. However, the results from this study of the hyperdiploid cell fraction showed that the increased sensitivity resulting from the use of CK5 was not clinically useful because of the decrease in specificity.