TRYPTASE AND IGE CONCENTRATIONS IN THE RESPIRATORY-TRACT OF INFANTS WITH ACUTE BRONCHIOLITIS

It has been proposed that a specific IgE response contributes to the i mmunopathology of acute respiratory syncytial virus (RSV) bronchioliti s but previous work has been difficult to replicate. Indirect evidence that might support this contention was sought by measuring total IgE concentrations in bronchoalveolar lavage (BAL) samples obtained from i ntubated infants and by attempting to detect mRNA for IgE in cells obt ained from both the upper and lower respiratory tract. Evidence of sig nificant mast cell activation was sought by measuring tryptase concent rations in BAL fluid and serum. Detectable concentrations of IgE were found in two of seven BAL samples obtained more than five days after i ntubation and mRNA for IgE was demonstrated in three of six BAL sample s and three of six samples obtained from the upper respiratory tract. Tryptase was detectable in 11 of 12 BAL samples with the two highest v alues detected on day 1. These values were raised compared with contro l samples but were not such to suggest A Swarbrick that mast cell degr anulation is the major contributor to the inflammatory process. These results suggest that IgE may be produced in the airways of infants in response to RSV infection. The relationships between IgE production, R SV infection, and symptoms of acute bronchiolitis remain obscure.