IN-SITU CDNA POLYMERASE CHAIN-REACTION A NOVEL TECHNIQUE FOR DETECTING MESSENGER-RNA EXPRESSION

We report a novel method for detecting intracellular messenger RNA by combining the techniques of in situ hybridization and polymerase chain reaction (PCR) (in situ CDNA PCR). The technique could detect low abu ndancy signals and distinguish different levels of gene expression. We examined the expression of the functional markers of activated cytoto xic T lymphocytes, granzyme A, and perforin in human lymphocytes from in vitro cultures. The amplification products were found in the cells and the supernatants, with the distribution critically affected by the protease digestion conditions. The specificity of amplification was c onfirmed by electrophoretic analysis and Southern blotting. We conclud e that the in situ CDNA PCR technique offers a sensitive method of mea suring the frequency of signal-expressing cells and has significant re search and clinical applications.