Expression of Fas-L mRNA induced by ATGs. (Left) PBL were cultured in presence of medium alone, ATG no. 95-07 (100 μg/mL) or PHA (5 μg/mL) for 3 days. Dead cells were removed, and viable cells were stimulated with normal rabbit IgG at 100 μg/mL, ATG no. 95-07 at 10 μg/mL and 100 μg/mL or PHA at 5 μg/mL for 6 hours. (Right) Freshly isolated PBL were stimulated with normal rabbit IgG at 100 μg/mL or ATG no. 95-07 at 10 μg/mL and 100 μg/mL for 6 hours. mRNA of each sample was amplified by RT-PCR as described in Materials and Methods with primers specific for actin or Fas-L. The number of amplification cycles selected within the exponential phase of PCR was 29 for actin and 32 for Fas-L. The PCR products were separated on 2% agarose gel and the PCR signal intensities were quantified by scanning the negative film. Results are expressed as the ratio of absorbance of Fas-L/absorbance of actin (mean ± SEM of three experiments).