Effect of BCG vaccination in asthmatic schoolchildren

Abstract

Recent studies have explored the effect of Bacilli Calmette-Guerin (BCG) or Mycobacterium vaccae vaccination in asthmatic patients, yielding conflicting results. We investigated the effect of BCG vaccination in asthmatic schoolchildren, especially focusing on the cytokine pattern released by mononuclear cells. After a 1-yr run-in period, 67 asthmatic schoolchildren received intradermal immunization with BCG (33 patients) or placebo (34 patients). Both groups were followed during 1 yr. Serum immunoglobulin E (IgE) levels did not change after BCG (407.1 ± 86.6 vs. 415.1 ± 86.7 IU/ml, mean ± s.e.m.), but increased after placebo (406.7 ± 67.0 vs. 619.7 ± 90.7 IU/ml, p = 0.001) administration. Interleukin (IL)-4 and interferon (IFN)-γ measured in the supernatant of stimulated cultured blood mononuclear cells did not change in the BCG group (10.8 ± 2.3 vs. 17.9 ± 5.7 pg/ml, and 348.6 ± 118.0 vs. 354.8 ± 139.0 pg/ml, respectively), while in the control group IL-4 increased (from 6.7 ± 1.3 to 16.1 ± 6.0 pg/ml, p < 0.05), and IFN-γ decreased (from 279.9 ± 82.1 to 232.1 ± 109.6 pg/ml, p = 0.01). In comparison with their initial status, most patients maintained the same asthma severity and the same proportion of emergency room visits at the end of the study. The proportion of those in whom asthma improved or worsened was the same in both groups. We concluded that, contrary to the common hypothesis, BCG vaccination in asthmatic children was unable to cause a long-term reinforcement of Th1 response, although it could avoid the increased Th2 response observed in control patients.