Presence of high contents of thymus and activation-regulated chemokine in platelets and elevated plasma levels of thymus and activation-regulated chemokine and macrophage-derived chemokine in patients with atopic dermatitis.
BACKGROUND
T(H)2 cells and eosinophils selectively express CC chemokine receptor 4 and CCR3, respectively, and their chemokine ligands are likely to play important roles in the pathogenesis of atopic dermatitis (AD).


OBJECTIVE
The purpose of this study was to demonstrate the presence of thymus and activation-regulated chemokine (TARC) in platelets and its release during clotting and to evaluate the circulating levels of TARC, macrophage-derived chemokine (MDC), and eotaxin in control subjects and patients with AD.


METHODS
We compared plasma and serum contents of TARC, MDC, and eotaxin. We measured TARC contents in platelet lysates. We analyzed the correlation of plasma levels of TARC, MDC, and eotaxin with various clinicolaboratory parameters in patients with AD.


RESULTS
Serum contents of TARC rapidly increased during clotting, whereas those of MDC and eotaxin increased only slightly. We demonstrated that platelets contained TARC, and its levels were dramatically elevated in patients with AD. Platelets also released TARC on stimulation with thrombin. We therefore evaluated circulating levels of these chemokines in control subjects and patients with AD by using plasma samples. Plasma TARC levels were significantly increased in patients with AD (P <.0001) and showed significant correlations with severity scoring of atopic dermatitis (SCORAD) index (r = 0.665, P <.00001), serum lactate dehydrogenese levels (r = 0.696, P =.00001), eosinophil counts (r = 0.381, P =.007), and platelet counts (r = 0.562, P <.0001). Similarly, plasma MDC levels were significantly increased in patients with AD (P <.0001) and showed significant correlations with SCORAD index (r = 0.727, P <.0001), serum lactate dehydrogenese levels (r = 0.861, P <.0001), eosinophil counts (r = 0.505, P =.005), and platelet counts (r = 0.370, P =.01). On treatment, plasma TARC and MDC levels were dramatically decreased in accordance with improved SCORAD scores (P =.0012 and P =.0007, respectively). On the other hand, plasma eotaxin levels did not show any significant increase or correlation with any of the clinical parameters in patients with AD.


CONCLUSIONS
Platelets from patients with AD contain high levels of TARC. Thus platelets might play an important role in AD pathogenesis by releasing T(H)2-attracting TARC on activation. Furthermore, circulating levels of TARC and MDC, but not those of eotaxin, correlate well with the disease activity of AD.
Department of Pediatrics and Allergy, National Mie Hospital, Tsu, Japan.
Takao
T
Fujisawa
Ryuichi
R
Fujisawa
Yoshiko
Y
Kato
Takashi
T
Nakayama
Atsushi
A
Morita
Hajime
H
Katsumata
Hisashi
H
Nishimori
Kousei
K
Iguchi
Hitoshi
H
Kamiya
Patrick W
PW
Gray
David
D
Chantry
Ryuji
R
Suzuki
Osamu
O
Yoshie
D000293:Adolescent; D000328:Adult; D001777:Blood Coagulation; D001792:Blood Platelets / Q000378:metabolism*; D054413:Chemokine CCL11; D054414:Chemokine CCL17; D054422:Chemokine CCL22; D019742:Chemokines, CC / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D003876:Dermatitis, Atopic / Q000097:blood / Q000276:immunology / Q000503:physiopathology*; D006801:Humans; D012720:Severity of Illness Index
C515456:CCL11 protein, human; C106230:CCL17 protein, human; C515482:CCL22 protein, human; D054413:Chemokine CCL11; D054414:Chemokine CCL17; D054422:Chemokine CCL22; D019742:Chemokines, CC