Induction of IL-1β mRNA in human PBMC exposed to CSA. (A) Total RNA isolated from PBMC cultured in the presence of CSA (1 mg/mL), PHA (1 μg/mL), or both, was subjected to Northern blot hybridization using IL-1β cDNA as a probe. The positions of the 28S and 18S ribosomal RNAs are indicated. Relative amounts of RNA loaded in each lane are visualized in the lower panel by methylene blue staining. (B) The intensities of the IL-1β hybridization signals shown in (A) were measured using an InstantImager analyzer, and the results were plotted as a histogram to highlight the relative IL-1β mRNA levels.