Passive cutaneous anaphylaxis (PCA) and specific IgE in cystic fibrosis and their heterozygotes.

The serum from 75% of the patients with cystic fibrosis (C.F.) who 
had a positive prick test in their skin to at least 
one or more antigens, together with elevated concentrations of total serum 
IgE, also gave strong immediate PCA reactions in the baboon skin 
to Aspergillus fumigatus, bovine serum albumin and egg albumin. Of the 
C.F. patients, 37% also had elevated serum specific IgE to A. 
fumigatus whereas only 8-10% had either raised specific IgE or PCA 
reaction to Dermatophagoides pteronyssinus. Abolition of the PCA activity by incubating 
the C.F. sera or sputum at 56 degrees C suggested that 
the reaginic antibody was IgE rather than IgG4. PCA reactions to 
a number of allergens could be detected in both the C.F. 
sputum and saliva. Several of the C.F. heterozygotes had a strongly 
positive history of allergy and a significant number of these heterozygotes 
had an elevated serum total IgE as well as positive PCA 
to Timothy grass pollen or to D. pteronyssinus similar to the 
patients with asthma or hay fever. Three C.F. patients who died 
gave strong prick test reactions to several allergens and their sera 
also had raised serum IgE and positive PCA to at least 
three different allergens, suggesting that immediate hypersensitivity is of some significance 
in patients with C.F. 