Increased sensitivity to IL-4 in patients with allergic bronchopulmonary aspergillosis.
BACKGROUND
Allergic bronchopulmonary aspergillosis (ABPA) is characterized by a heightened Th2 CD4+ cell response to Aspergillus fumigatus allergens and a hyper-IgE state compared to atopic asthmatic and cystic fibrosis patients without ABPA. We hypothesized that one reason for this response is increased sensitivity to IL-4 in ABPA, resulting in increased expression of CD23 and CD86, leading to a positive amplification mechanism which increases Th2 CD4+ T cell responses.


METHODS
Peripheral blood mononuclear cells isolated from 10 ABPA, 9 atopic, and 8 nonatopic subjects and stimulated for 48 h with varying concentrations of rIL-4 ranging from 0.1 to 50 ng/ml. The percentages of CD23+ and CD86+ B cells and the number of CD23+ molecules on CD20+ and CD86+CD20+ B cells were quantified by flow cytometry.


RESULTS
Total serum IgE levels were elevated in ABPA patients compared to atopic and nonatopic controls. At day 0 prior to culture, CD23 molecules per CD20+ B cell were significantly elevated in ABPA patients compared to atopic and to nonatopic patients. CD23 molecules per CD20+ B cell in ABPA and atopic patients decreased after 48 h in culture without IL-4 added and were similar. With IL-4 stimulation, ABPA patients had significantly increased rates of CD23 expression per B cell compared to atopic and nonatopic subjects (p < 0.001). Furthermore, ABPA had significantly increased numbers of CD23+ molecules per B cell and CD86+ B cell following IL-4 stimulation compared to atopic and nonatopic patients. Both ABPA and atopic patients at day 0 prior to culture had increased expression of CD86+ and CD23+CD86+ B cells compared to nonatopic patients. After 48 h in culture without IL-4, the percentages of CD86+ and CD23+CD86+ B cells decreased in ABPA and atopic patients. After stimulation with IL-4, ABPA patients had significant upregulation of CD23+CD86+ B cells compared to atopic and nonatopic patients. Similarly, the number of CD23 molecules per CD86+CD20+ B cell was significantly upregulated following IL-4 stimulation in ABPA patients compared to atopic and to nonatopic subjects.


CONCLUSIONS
This is the first study to demonstrate that ABPA patients have increased sensitivity to IL-4 stimulation compared to other atopic individuals, such that ABPA > atopic >> nonatopic patients. The B cells from ABPA patients were significantly more sensitive to IL-4 stimulation compared to atopic and nonatopic patients with upregulation of CD23 and CD86 expression. ABPA subjects had increased CD86+ and CD23+CD86+ B cell expression on day 0 prior to culture and with upregulation of CD23+ molecules on CD86+CD20+ B cells. IL-4 also stimulated upregulated CD86+ expression on B cells in atopic patients with little effect on nonatopic patients. This study supports the premise that IL-4, IL-4R alpha and CD86 are central targets in the treatment of ABPA and atopic disease.
Khan
S
S
Division of Allergy, Department of Pediatrics, St. Louis University Health Sciences Center, St. Louis, MO, USA.
McClellan
J S
JS
Knutsen
A P
AP
D000293:Adolescent; D000328:Adult; D000368:Aged; D015703:Antigens, CD / Q000378:metabolism; D018951:Antigens, CD20 / Q000378:metabolism; D001229:Aspergillosis, Allergic Bronchopulmonary / Q000276:immunology*; D001249:Asthma / Q000276:immunology; D016175:B-Lymphocyte Subsets / Q000187:drug effects / Q000276:immunology; D051940:B7-2 Antigen; D016022:Case-Control Studies; D002648:Child; D003550:Cystic Fibrosis / Q000276:immunology; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000276:immunology; D066298:In Vitro Techniques; D015847:Interleukin-4 / Q000494:pharmacology*; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D008875:Middle Aged; D017455:Receptors, IgE / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D018418:Th2 Cells / Q000187:drug effects / Q000276:immunology
D015703:Antigens, CD; D018951:Antigens, CD20; D051940:B7-2 Antigen; C497964:CD86 protein, human; D008562:Membrane Glycoproteins; D017455:Receptors, IgE; D011994:Recombinant Proteins; D015847:Interleukin-4