Effect of specific or random c-DNA priming on sensitivity of tyrosinase nested RT-PCR: Potential clinical relevance

The reverse transcriptase polymerase chain reaction (RT-PCR) can be of clin ical relevance in identifying malignant melanoma cells in blood or tissues of patients at risk for disseminated melanoma. The diagnostic value of this marker however, is still controversial. The objective of this study was to compare and quantify the difference in sensitivity of the nested RT-PCR fo r tyrosinase, with respect to the method utilized to produce the template c -DNA. We found a difference of a factor 10 in favor of a specific priming v ersus a random one. We concluded that this difference can be exploited in t he analysis of blood samples. However; in the analysis of lymph node specim ens, where the chance of positivity due to tyrosinase positive non-melanoma cells is much higher, the choice of a highly sensitive assay should be mad e with caution.