Lowered yields of virus-induced interferon production in leukocyte cultures and risk of recurrent respiratory infections in children

Objective: To study the correlation between the yield of virus-induced interferon (IFN) production in leukocyte cultures and the risk of recurrent respiratory infections. Methods: A sample of 71 consecutive children enrolled in the Finnish Otitis Media Cohort Study were selected. Children suffering from frequently recurring respiratory infections (FRRIs) were defined as the highest quintile of the entire cohort of 329 children, as regards the number of upper respiratory infections (URIs) and/or episodes of acute otitis media (AOM) during the follow-up period from 2 to 24 months. Results: In the sample of 71 children, there were 18 children with FRRI (≥9 URI and/or ≥4 AOM). Leukocyte cultures, prepared from blood drawn from these 18 children at 6 months of age, produced lower yields of IFN than those of the remaining 53 children, when stimulated with adenovirus (P<0.001), coronavirus (P<0.001) or rhinovirus (P=0.002). The difference in IFN yields was even greater (P<0.001 with all three viruses) if the comparison was made between children with FRRI and those with no or maximally one URI during the follow-up period. When the IFN production capacity induced by rhinovirus was measured at the age of 24 months, a statistically significant difference between the children with FRRI and the others was also seen (P=0.002). Influenza A virus-induced IFN production capacity did not differ between the groups at either age (P=0.209). Conclusions: Lowered IFN responses in children suffering from recurrent URIs and/or AOM may, in a subgroup of the children, be due to a genetic property of the child. However, because of the great interindividual variations, we cannot use the IFN production capacity as such for prediction of forthcoming respiratory infections and/or otitis media.