Differential mediator release from basophils of allergic and non-allergic asthmatic patients after stimulation with anti-IgE and C5a.

The differentiation between allergic and non-allergic asthma is a common and important challenge for the clinician. Until now, no in vitro diagnostic characteristics have been described to distinguish between these types. To examine the diagnostic value of a basophil stimulation test, we compared anti-IgE- and C5a-induced mediator release from peripheral blood leucocytes in different types of bronchial asthma. Peripheral blood leucocytes (PBL) from 10 aspirin-sensitive asthmatics (ASA), 12 non-allergic asthmatics without aspirin intolerance (NAA), seven allergic asthmatics (AA), and nine healthy controls were prepared by dextran sedimentation. After priming with interleukin-3 (IL-3) PBL were stimulated with anti-IgE and C5a, and the release of histamine (HR) and sulfidoleukotrienes (LTR) in the supernatant was compared. Additionally, purified leucocyte fractions were studied to determine the cellular source of mediator release. Upon stimulation with anti-IgE LTR was slightly, but not significantly, lower in ASA and NAA compared to AA and controls. In contrast, C5a-triggered LTR was significantly higher in ASA (14.4 +/- 12.88 pg/105 cells) and NAA (22.9 +/- 22.61 pg/105 cells) than in AA (9.6 +/- 3.29 pg/105 cells) and controls (7.5 +/- 7.19 pg/105 cells) (P < 0.05). This difference between ASA and NAA vs. AA and controls was even more pronounced when determining the quotient C5a-/anti-IgE-induced LTR (P < 0.001). At an optimal cut-off point of 1.0, calculated by relative operating characteristics (ROC) analysis, the positive predictive value for a donor to belong to ASA or NAA was 0.94. No significant differences could be found in HR between the asthmatic patient groups and healthy controls in either condition. As cellular source of LTR and HR the basophil could be determined. Determination of anti-IgE- and C5a-induced LTR from basophils allows us to discriminate between allergic and non-allergic asthmatic patients. For diagnostic purposes the quotient C5a-/anti-IgE-induced LTR is more significant than considering a single parameter. ASA cannot be distinguished from NAA.