Background: Activity of immunoglobulin (Ig)E-dependent histamine-releasing factor (HRF) is dependent on the IgE molecules bound to the surface of basophils. Sera capable of passively sensitizing basophils to release histamine to HRF were designated IgE+ sera. IgE+ and HRF have been suggested to play a role in late allergic reaction (LAR). Objective: The working hypothesis was tested that IgE+ induces a LAR. Further, activity of HRF produced by mononuclear cells (HRFmn) was compared with that of recombinant HRF p23. Methods: Atopic patients (n = 82) were bronchially provoked with Dermatophagoides pteronyssinus extract and the change in forced expiratory volume in 1 second was monitored. A LAR was defined as forced expiratory volume in 1 second as percentage of baseline <80% 4 to 10 hours after allergen challenge. The presence of HRF-responsive IgE in serum was determined using basophils sensitized in vitro by serum. Results: The presence of HRFmn-responsive IgE (IgEmn+) in serum was shown not be essential for a LAR: 63% of the patients with a LAR had no IgEmn+ in their serum. Further, 71% of patients with IgEmn+ did not have a LAR. HRFmn and recombinant HRF p23 were not equivalent in the bioassay: serum of 38 of 82 atopic patients sensitized basophils to release histamine to HRFmn, whereas this was found with serum of 1 of 82 patients to HRF p23. Conclusions: The results do not support the hypothesis that IgEmn+ induces a LAR, but do not exclude the alternative hypothesis that HRFs are released during a LAR and contribute to asthma severity.
ASJC Scopus subject areas
- Immunology and Allergy
- Pulmonary and Respiratory Medicine