Interleukin 16 and T-cell chemoattractant activity in bronchoalveolar lavage 24 hours after allergen challenge in asthma.
IL-16 has been shown to be one of the earliest CD4(+) cell chemoattractants present in BAL 4-6 h after antigen challenge but little is known about its persistence and biological activity after 6 h. We determined the concentration of IL-16 using ELISA and the T-cell chemoattractant activity using a modified Boyden chamber assay in unconcentrated BAL fluid from 13 patients with mild asthma and 9 nonatopic control subjects at baseline and 24 h after segmental allergen or saline challenge. Furthermore, the percentage of IL-16-producing T cells was determined in the different samples of BAL fluid using a flow cytometric intracellular cytokine assay. Although no substantial levels of IL-16 protein were detectable in BAL fluid from control subjects and patients with asthma at baseline and after saline challenge, IL-16 concentrations were significantly elevated in patients with asthma after allergen challenge (median, 97 pg/ml; range, 38-362 pg/ml; p < 0.01). Furthermore, there was an increased T-cell chemoattractant activity after allergen challenge in patients with asthma (p < 0.01), which could be blocked by preincubation with anti-IL-16 antibodies and which correlated significantly with the IL-16 protein levels (R = 0.90, p < 0.01) and with the level of Fas ligand expression on BAL CD4(+) cells (R = 0. 80, p < 0.05). A high percentage (mean 70-90%) of CD4(+) and CD8(+) cells stained positively for IL-16 in both patients with asthma and control subjects without differences after allergen or saline challenge. These data demonstrate that the increased chemotactic activity for T cells in patients with asthma is mainly attributable to IL-16. Although T cells by themselves are able to produce IL-16, other cells, such as epithelial cells, have to be considered as further sources for this cytokine in patients with asthma.
Krug
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Departments of Respiratory Medicine and Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany. Krug.Norbert@T-online.de
Cruikshank
W W
WW
Tschernig
T
T
Erpenbeck
V J
VJ
Balke
K
K
Hohlfeld
J M
JM
Center
D M
DM
Fabel
H
H
D000328:Adult; D001249:Asthma / Q000276:immunology*; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry* / Q000166:cytology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002633:Chemotaxis; D004804:Eosinophils; D005260:Female; D006801:Humans; D019410:Interleukin-16 / Q000032:analysis / Q000276:immunology*; D008297:Male; D013997:Time Factors
D019410:Interleukin-16