AN IMPROVED AND COMBINED REVERSE TRANSCRIPTION-POLYMERASE CHAIN-REACTION ASSAY FOR RELIABLE DETECTION OF METASTATIC MELANOMA-CELLS IN PERIPHERAL-BLOOD

The application of reverse transcription-polymerase chain reaction (RT -PCR) for detection of metastatic melanoma cells in peripheral blood h as been used by a number of different scientific groups with both enco uraging and discouraging results. We describe an improved, combined RT -PCR assay for tyrosinase mRNA, which can detect a single, viable mela noma cell in 10-15 mi of peripheral blood. The assay has been found to be highly sensitive, reproducible, cost-effective and clinically appl icable. Furthermore, we developed a simple but effective procedure whi ch prevents carry-over contamination. We present evidence indicating t hat the chance of obtaining normal melanocyte contamination with the n eedle prick during blood sampling is only 2% among all skin categories . It was found that the phenomenon of illegitimate transcription does not contribute to sporadic false positives. We conclude that the assay , as described here, is of clinical relevance and is a potentially pow erful tool for studying various aspects of melanoma biology.