A potential diagnostic tool for prostate cancer detection. The present invention provides a method for the isolation of epithelial cells from a solution and a method for detecting the presence of cancerous vascular endothelial cells using J591, a monoclonal antibody, and a magnetic activated cell sorter. The invention can be used for the diagnosis and monitoring of treatment of prostate cancer. The method employs a biological agent, such as an antibody or a binding portion of an antibody, to bind an extracellular domain of the prostate specific membrane antigen (PSMA) protein on such cells. The biological agent is contacted with cells under conditions that allow both binding of the biological agent to the PSMA protein on the cells for detecting and ablating or killing of the cells. The biological agent may also be used to detect normal, benign hyperplastic, or cancerous prostate epithelial cells, or portions thereof, in a biological sample. Ongoing investigations are attempting to combine this approach with gene screening to detect prostate cancer specific genes.