Expression of STAT4 mRNA by PBMCs. (A) Total RNA was extracted from PBMCs of 3 healthy control subjects (lanes 1-3) or 3 patients with lymphoma after transplantation (lanes 4-6), reverse transcribed to cDNA, subjected to 25 cycles of PCR amplification, and resolved by electrophoresis as described in “Patients, materials, and methods.” The specific bands corresponding to the amplified STAT4 cDNA (upper) or amplified GAPDH cDNA (lower) are indicated by arrows. (B) Intensities of the STAT4 and GAPDH bands were measured by densitometry. Values shown are mean ± SD of the ratio of the intensity of STAT4 to GAPDH bands.