Reverse transcriptase-polymerase chain reaction analysis of IL-12 p35 subunit mRNA expression by human mononuclear cells obtained from ICU patients. Specific fragments of IL-12 p35 were evident on Southern blotting (arrow), and upregulation was detected on day 8 in patients receiving cimetidine. Such fragments were not found in cells from patients treated with famotidine. Lanes 1 and 2 are cimetidine treatment on day 1 and day 8. Lanes 3 and 4 are negative controls for lanes 1 and 2, respectively. Lanes 5 and 6 are β-actin for lanes 1 and 2, respectively. Lanes 7 and 8 are famotidine treatment on day 1 and day 8. Lanes 9 and 10 are negative controls for lanes 7 and 8, respectively. Lanes 11 and 12 are β-actin for lanes 7 and 8, respectively. Lane M contains size markers of 123 bp.