Increased sensitivity to IL-4 in cystic fibrosis patients with allergic bronchopulmonary aspergillosis.
BACKGROUND
Allergic bronchopulmonary aspergillosis (ABPA) is characterized by a heightened Th2 CD4+ T-cell response to Aspergillus fumigatus allergens and a hyper-immunoglobulin (Ig)E state compared with cystic fibrosis patients without ABPA. We hypothesize that one reason for this response is increased sensitivity to interleukin (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
Peripheral blood mononuclear cells (PBMC) were isolated from seven ABPA CF and 19 non-ABPA CF patients and 16 nonatopic controls and stimulated with rIL-4 (range 0.1-10 ng/ml) and rIL-13 (range 1-10 ng/ml) for 48 h. The number of CD23 molecules and percentages of CD23+ B cells were quantified by flow cytometry. Both phorbol 12-myristate 13-acetate (PMA)/ionomycin (IO) and antigen stimulated, toxoid and Asp f2/f3/f4, PBMC were examined for cytoplasmic cytokine synthesis enumerated by cytokine staining using flow cytometry to measure Th2 and Th1 CD3+ T cells.


RESULTS
The numbers of CD23 molecules on B-cells were significantly elevated at time 0 in ABPA CF patients compared with both non-ABPA CF patients and nonatopic controls. Following IL-4 stimulation in vitro, the numbers and percentages of CD23 expression on B cells were significantly up-regulated in ABPA CF patients compared with non-ABPA CF patients and controls. The IL-13 stimulation up-regulated CD23 expression; however, there was no significant difference in ABPA CF patients compared with non-ABPA CF patients and controls. The percentages of interferon (IFN)-gamma+ CD3+T cells following PMA/IO stimulation were significantly decreased in both ABPA and non-ABPA CF patients compared with controls. There were no significant differences of IL-4+ and IL-13+ CD3+ T cells between ABPA and non-ABPA CF patients. When tetanus toxoid stimulated T cells were examined, both ABPA and non-ABPA CF patients had significantly decreased IFN-gamma+ CD3+ T cells compared with controls. In Asp f2/f3/f4 stimulated T cells, ABPA CF patients had significantly increased IL-4+ CD3+ T cells compared with non-ABPA CF patients and controls.


CONCLUSIONS
ABPA CF patients have increased sensitivity to IL-4 but not to IL-13 up-regulation of CD23 molecules compared with non-ABPA CF patients. There were decreased percentages of IFN-gamma+ and IL-2+ Th1 T cells in CF patients compared with nonatopic controls but similar percentages of IL-4+ Th2 T cells in all three groups. However, ABPA CF patients had increased frequency of Aspergillus-stimulated Th2 T cells. This indicated that there is skewing of Th2 T cells in ABPA CF patients. Thus, in CF ABPA patients there is increased Th2 T cells and increased sensitivity to IL-4.
Knutsen
A P
AP
Division of Allergy and Immunology, Saint Louis University Health Sciences Center, St Louis, MO 63110, USA.
Hutchinson
P S
PS
Albers
G M
GM
Consolino
J
J
Smick
J
J
Kurup
V P
VP
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D000946:Antigens, Fungal / Q000032:analysis / Q000276:immunology; D001229:Aspergillosis, Allergic Bronchopulmonary / Q000150:complications / Q000276:immunology*; D016022:Case-Control Studies; D002478:Cells, Cultured; D002648:Child; D003550:Cystic Fibrosis / Q000150:complications / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007073:Immunoglobulin E / Q000032:analysis; D015847:Interleukin-4 / Q000494:pharmacology*; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology; D008297:Male; D008875:Middle Aged; D011336:Probability; D017455:Receptors, IgE / Q000276:immunology / Q000378:metabolism; D012016:Reference Values; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D018417:Th1 Cells / Q000187:drug effects* / Q000276:immunology; D018418:Th2 Cells / Q000187:drug effects* / Q000276:immunology
D000946:Antigens, Fungal; D017455:Receptors, IgE; D015847:Interleukin-4; D007073:Immunoglobulin E