Effect of CD15 cross-linking on IL-1β mRNA stability. CD15 cross-linking reduced IL-1β degradation. Mono Mac 6 cells (2 × 10⁶/condition) were incubated with an anti-CD15 MoAb (PM81, 10 μg/mL) for 20 minutes followed by F(ab) ′₂ goat antimouse IgM (10 μg/mL). Actinomycin D (5 μg/mL) was added to cells 2 hours after the CD15 cross-linking and total RNA was extracted at the designated time (hours). The level of steady-state of IL-1β mRNA was estimated by quantitative RT-PCR. The percent of maximal-induced IL-1β was calculated using the 2-hour time point as the zero time reference for comparison with the residual IL-1β mRNA at the later time points. Shown is a representative experiment of two separate studies.