Bronchial challenge with purified protein derivative of Mycobacterium tuberculosis in asthma

Response to bronchial challenge (BC) with purified protein derivative of Mycobacterium tuberculosis (PPD), was studied in children with bronchial asthma and correlated with Mantoux test and serum immunoglobulin E (IgE) against PPD (PPD-Sp IgE). Nearly 59% patients with bronchial asthma and 12.2% patients with pulmonary tuberculosis gave positive BC. Children with extra-pulmonary tuberculosis and normal children did not show positive BC. In asthma, 25% gave early (EAR), 50% gave late (LAR) and 25% gave both early and late (DAR) asthmatic response. Forced expiratory flow volumes in 1 sec (FEV.1) of 13 age and sex matched asthmatic and normal children showed similar volumes before BC, however, the values were significantly lower in asthma at 20 min (p less than 0.005) and 24 h (p less than 0.005) after BC. There was no relationship between response to BC and the severity or chronicity of asthma. PPD-Sp IgE was estimated by the radioimmunoassay method (Pharmacia Diagnostics). It was detected in 75% with positive BC and none of the controls. The titre was of Phadebas RAST Class III in 66.7%, Class II in 22.2% and Class I in 11.1%. The presence of early Mantoux reactions, positive BC with PPD and serum PPD-Sp IgE suggest the existence of Type I or Arthus type of reactions to PPD, which could cause hyperreactive airways in some cases of asthma.