Comparison of the quantitative competitive and semiquantitative RT-PCR methods for the determination of interferon-gamma mRNA levels in AIDS-free HIV-infected individuals

IFN-gamma mRNA expression was evaluated in nonstimulated peripheral blood m ononuclear cells (PBMC) of HIV-infected and seronegative individuals using quantitative competitive and semiquantitative RT-PCR and the sensitivity of these methods was compared. A significant correlation was found between qu antitative competitive and semiquantitative RT-PCR in samples of both HIV-s eronegative (P = 0.004) and HIV-infected individuals (P = 0.0004). PBMC fro m HIV-infected individuals presented a remarkable increase of IFN-gamma mRN A expression, as determined by both types of RT-PCR methods. Semiquantitati ve RT-PCR even without an internal standard is also acceptable for measurin g cytokine mRNA expression, but less reliable if small amounts are quantifi ed. Moreover, we found that increased IFN-gamma mRNA expression is independ ent of CD4+ cell count in AIDS-free HIV-infected patients.