Table 2.

Effect of PDE inhibitors on the generation of histamine, IL-13 and IL-4 from basophils activated with IL-3

	% inhibition
PDE inhibitor	Histamine	IL-13	IL-4
8-Me-IBMX	31±7	16±8	9±15
siguazodan	27±7	−2±7	−1±2
Org 30029	52±11*	32±6**	64±7*
rolipram	66±12**	56±5**	81±3**
zaprinast	14±7	10±4	34±11
theophylline	94±4**	65±6**	92±4**

Basophils 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 IL-3 (100 ng ml⁻¹) for 24 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 28±6% histamine release, 237±48 pg of IL-13 per 10⁶ basophils, 24±8 pg of IL-4 per 10⁶ basophils. Although IL-3 induced histamine release in all seven experiments, in one experiment no IL-13 generation was detected and in three experiments no IL-4 generation was obtained. Thus, values are means±s.e.m. from seven (histamine), six (IL-13) and four (IL-4) experiments. Asterisks denote

^*P<0.05

^**P<0.01.