Abstract: AIM: To investigate the mechanism of anti-inflammatory action of theophylline on asthma.METHODS: Nineteen asthmaticPatients were adminis-tered 200mg sustained-release theophylline twice daily for 4 weeks.The numbers orlevels of CD4⁺Tlymphocytes,eosinophils,interleukin (IL)-5 and interferon gamma(IFN-γ)in sputumPre- andPost-administration were measured by direct immunofluorescene technique,Wright' s stain and enzyme-linked immunosorbent assay,respectively.The symptom scores andlung function were also evaluated.RESULTS: Theophylline treatment sig-nificantly improved symptom scores,FEV 1.0 and FEV 1.0 %(P<0.05)and reduced sputum eosinophils (P<0.01)in asthmaticPatients.These were accompaniedwith a de-crease in sputum IL-5level(P<0.01),but sputum CD4⁺Tlymphocytes and IFN-γhad no significant change(P>0.05).The mean (range)serum theophylline con-centration in final steady state was 7.9 (3.9 -14.7)mg·L^-1.CONCLUSION: The anti-inflammatory actionof theophylline in asthma may result from reduction of IL-5Production in the airways.

Key words: pharmacodynamics, asthma, theophyl-line, interleukin-5, interferon gamma, CD4⁺Tlympho-Cyte