Cross-linking of the high-affinity IgE receptor induces the expression of cyclo-oxygenase 2 and attendant prostaglandin generation requiring interleukin 10 and interleukin 1β in mouse cultured mast cells

When mouse bone marrow-derived mast cells (BMMC) developed in interleukin (IL)-3 were activated with IgE and antigen (IgE/antigen) in the presence of both IL-10 and IL-1β, two sequential phases of prostaglandin (PG)D₂ generation were elicited, in which the first phase occurred by 1 h and the second phase from 2 to 10 h. The delayed phase of PGD₂ generation was accompanied by a marked induction of cyclo-oxygenase (COX)-2 mRNA, which reached a peak at 1–2 h, followed by that of its protein from 2–10 h, with a peak at 5 h. The immediate phase of PGD₂ generation was completely abrogated by the irreversible inhibition of pre-exisiting COX-1 by aspirin pretreatment, whereas the delayed phase of PGD₂ generation was almost undetectable in the presence of the COX-2 inhibitor NS-398. A detailed analysis of the individual effects of IgE/antigen, IL-10 and IL-1β on COX-2 expression revealed that IgE/antigen and IL-10 each initiated and stabilized COX-2 mRNA expression, leading to an increase in the expression of its protein. Conversely, IL-1β stabilized the COX-2 protein without affecting its mRNA level. The induction of COX-2 by IgE/antigen with IL-10 and IL-1β preceded the induction of transcripts for endogenous cytokines such as IL-6, IL-1β and IL-10. The inhibition of PGD₂ generation by indomethacin did not affect the induction of COX-2 or these cytokines. Thus the two major delayed-phase responses of BMMC after IgE-dependent activation, namely COX-2-dependent PGD₂ generation and cytokine production, are regulated independently.