Canadian Health&Care; Mall

Asthmatic patients appear to have more viral respiratory infections than do normal subjects, and those respiratory infections may trigger the exacerbations of asthma. Thus, there is a possibility that the inhibition of NK cell activity, one of the primary defense mechanisms, may induce more frequent infections and asthmatic attacks. Secondly, some evidence has been presented that the asthmatic population has a lower incidence of malignancies than the normal population. On the other hand, Timonen and Stenius-Aarniala reported that asthmatic patients have increased NK cell activity. Because NK cells are also considered to be a primary defense mechanism for malignancies, the increased activity may contribute to the low incidence of malignancies. It is difficult to prove the contribution, but in the case of cimetidine, which can enhance the NK cell activity in vitro, administration of this drug reduced tumor formation in vivo.21 Thus, inhibition of NK cell activity may erase the beneficial aspect (te, low incidence of malignancies) in the asthmatic population. In summary, we have demonstrated that theophylline can inhibit NK cell activity at therapeutic concentrations. Such an effect may cause undesirable results described herein. Therefore, more studies concerning long-term follow-up on such aspects of chronic theophylline therapy will be needed to determine its position in the treatment of asthmatic patients.