High serum levels of additional IL-18 forms may be reciprocally correlated with IgE levels in patients with atopic dermatitis.
We established an ELISA system for determination of as yet unidentified species of interleukin 18 (IL-18), named IL-18 type 2, in human serum. Serum IL-18 levels and their effect on IgE levels were examined in 18 patients with atopic dermatitis (AD) with no other allergic symptoms. Three of these patients showed high IL-18 type 2 concentrations (25-100 ng/ml) in their blood serum, and this IL-18 type 2 was detectable only with our established ELISA system. In contrast, the level of the conventional form of IL-18 (type 1) was found to be 50-400 pg/ml in all patients by the commercially available ELISA. The levels of type 1 IL-18 showed no correlation with those of type 2 and approximately 2-fold higher in AD patients than in normal subjects. IL-12 p40 and IgE levels were correlated in the patients with no IL-18 type 2, and interestingly, relatively low IgE concentrations were detected in the three IL-18 type 2-positive patients. They showed considerable levels of IL-12 p40 unlike normal subjects. The IFNgamma-inducing activity of IL-18 type 2 was >100-fold less potent by weight ratio than that of a recombinant 'active' IL-18 preparation, even after the treatment with Caspase 1. Although the relationship between AD and serum IgE levels is not clear cut, IL-18 type 2 appears to play some roles in the Th2-polarization involving IgE production in association with immune responses occurring in local inflammatory milieu such as atopic lesions.
Shida
K
K
Department of Immunology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Higashinari-ku, 537-8511, Osaka, Japan.
Koizumi
H
H
Shiratori
I
I
Matsumoto
M
M
Kikkawa
S
S
Tsuji
S
S
Begum
N A
NA
Fukumori
Y
Y
Toyoshima
K
K
Seya
T
T
D000293:Adolescent; D000328:Adult; D000911:Antibodies, Monoclonal / Q000276:immunology; D020170:Caspase 1 / Q000378:metabolism; D003876:Dermatitis, Atopic / Q000097:blood / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood* / Q000276:immunology; D007371:Interferon-gamma / Q000096:biosynthesis / Q000097:blood; D018664:Interleukin-12 / Q000097:blood; D020382:Interleukin-18 / Q000097:blood* / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D020033:Protein Isoforms / Q000097:blood / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D011863:Radioimmunoassay
D000911:Antibodies, Monoclonal; D020382:Interleukin-18; D020033:Protein Isoforms; D018664:Interleukin-12; D007073:Immunoglobulin E; D007371:Interferon-gamma; D020170:Caspase 1