[In vitro detection of prostate cancer circulating cells by immunocytochemistry, flow cytometry and RT-PCR PSA]

To evaluate 3 in vitro methods detection (immunocytochemistry, flow cytometry and RT-PCR PSA) of circulating prostate cancer cells from a model of uncap dilution in immortalised lymphocytes.

In vitro comparison of 3 techniques (immunocytochemistry, flow cytometry, RT-PCR PSA) was performed from a range of dilutions of LbCap cells in immortalised human lymphocytes (concentration range: 1 LnCap cell per 100 lymphocytes to 1 LnCap cell per 100 million lymphocytes). Cells were detected by anti-PSA (prostate specific antigen) and PAP (prostatic acid phosphatase) antibody by immunochemistry, by fluorescent linked antipancytokeratin antibody by flow cytometry and RT-PCR PSA.

The limit of detection was 1 LnCap cell per 200,000 lymphocytes (1/2.10(5)) for immunochemistry, 1 LnCap cell per 1,000 lymphocytes (1/1.10(3)) for flow cytometry and 1 LnCap cell per 10 million lymphocytes (1/10(7)) for RT-PCR PSA.

RT-PCR, due to its most perceptible limit of detection, appears to be the method of choice for the detection of prostatic epithelial cells. Immunocytochemistry has the advantage of providing a quantitative approach. Flow cytometry is limited by the limit of detection of the apparatus used. The prognostic significance of detection of circulating prostate cancer cells remains to be clarified, but the detection of these cells and their correlation with the primary tumour will provide a better understanding of metastatic phenomena.