INDUCTION OF ALLERGEN-SPECIFIC IL-2 RESPONSIVENESS OF LYMPHOCYTES AFTER RESPIRATORY SYNCYTIAL VIRUS-INFECTION AND PREDICTION OF ONSET OF RECURRENT WHEEZING AND BRONCHIAL-ASTHMA

Background: In pediatric patients with bronchial asthma and/or atopic dermatitis, peripheral lymphocytes are activated if they are stimulate d with the responsible antigen, resulting in induction of responsivene ss to IL-2. Because some nursing infants experience recurrent wheezing after respiratory syncytial virus (RSV) infection, attention is being directed to progression of the disease to bronchial asthma. Objective s: The study was designed to elucidate the mechanism of the onset of a llergic diseases after RSV infection. Methods: We examined allergen-sp ecific IL-2 responsiveness induced in lymphocytes in the peripheral bl ood of infants after infection by RSV. The relationship between the on set of recurrent wheezing and antigen-specific IL-2 responsiveness was analyzed in 25 pediatric patients who could be followed up for 3 year s after RSV infection. Results: Stimulation of lymphocytes with ovalbu min, alpha-casein, and mite (Dermatophagoides farinae) antigens induce d significantly higher responsiveness to IL-2 in the RSV-infected infa nt group than in the healthy infant and disease control groups of the same age. There was no clear correlation between the IgE RAST scores f or D. farinae, ovalbumin, and alpha-casein and IL-2 responsiveness. Th e D. farinae-specific IL-2 responsiveness was significantly increased in the group with the symptom (16 patients) for a value of 1.64 +/- 0. 13 (mean +/- SEM) compared with the value of 1.31 +/- 0.21 in the asym ptomatic group (9 patients). The incidence of patients with positive t est results for IL-2 responsiveness was 68.8% in the symptomatic group and 44.4% in the asymptomatic group. Similarly, the ovalbumin-specifi c IL-2 responsiveness was significantly increased in the symptomatic g roup (1.63 +/- 0.17) compared with the asymptomatic group (1.12 +/- 0. 26). The incidence of patients with positive test results was 62.5% an d 22.2%, respectively. alpha-Casein-specific IL-2 responsiveness was a lso higher in the symptomatic group than in the asymptomatic group, bu t the difference was not statistically significant. In the patient gro ups with RSV infection, on the other hand, the D. farinae-, ovalbumin- , and alpha-casein-specific IL-2 responsiveness in the symptomatic gro up were all similar to that in the asymptomatic group were all similar to that in the asymptomatic group; no significant increases were dete cted. Conclusion: The results indicated that after RSV infection, lymp hocytes acquire specific susceptibility to D. farinae, a mite antigen, and food antigens, particularly ovalbumin. Hence, it is thought that positive IL-2 responsiveness specific for D. farinae and/or ovalbumin, detected several months after RSV infection, can be a prediction fact or for the onset of allergic diseases, such as received wheezing and b ronchial asthma.