Figure 2.

Effect of selective PDE inhibitors on (a) IL-4 generation and (b) histamine release from basophils. Cells were incubated for 15 min with the inhibitors, 8-methoxymethyl-IBMX (8-Me-IBMX; PDE1 inhibitor), siguazodan (PDE3 inhibitor), Org 30029 (mixed PDE3/4 inhibitor), rolipram (PDE4 inhibitor) zaprinast (PDE5 inhibitor) or theophylline (nonselective) before challenge with anti-IgE (1 : 100,000 or 1 : 10,000) for 4 h. All inhibitors were used at 10 μM except theophylline which was used at 1 mM. Values are expressed as the % inhibition of the control releases, which were for (a), 53±16 pg of IL-4 per 10⁶ basophils and for (b), 22±5% histamine release. Values are means±s.e.m., n=7. Asterisks denote; ^*P<0.05, ^**P<0.01.