Rationale ABPA is characterized by a heightened Th2 response to A. fumigatus allergens and a hyper-IgE state compared to patients without ABPA. We hypothesize that one reason for this response is increased sensitivity to IL-4 in ABPA resulting in increased expression of CD23 and CD86 and leading to a positive amplification mechanism that increases Th2 CD4+ T cell responses. Methods PBLs were stimulated with rIL-4 (1-10 ng/ml) and rIL-13 (1-10 ng/ml) for 48 hours. The number of CD23 molecules and percentages of CD23+ B cells were quantified by flow cytometry. Results Following IL-4 stimulation in vitro, the numbers and percentages of CD23 expression on B-cells and CD86+ B-cells were significantly up-regulated in ABPA CF patients compared to non-ABPA CF patients and controls. The slope of increase of CD23 molecules on B-cell was significantly increased in ABPA patients compared to non-ABPA patients. The percentages of CD86+ and CD23+CD86+ B-cells were significantly elevated on Day 0 in ABPA CF patients compared to non-ABPA CF patients. Furthermore, during flares of ABPA compared to remissions the number of CD23 molecules increased on total and CD86+ B-cells. Blockade of CD86 activation with anti-CD86 mAb inhibited IL-4 induced CD23 expression by 50%. With IL-13 stimulation, CD23 expression was up-regulated; however, there was no significant difference in ABPA patients compared to non-ABPA patients and controls. Conclusions ABPA CF patients have increased sensitivity to IL-4 stimulation with up-regulation of CD23 molecules compared to non-ABPA CF patients. During flares of ABPA, there is increased expression of CD23+ on B-cells.
Full conference title:
2004 American Academy of Allergy, Asthma, and Immunology Annual Meeting
- AAAAI 2004 (60th)