Luteolin, a flavonoid, inhibits CD40 ligand expression by activated human basophils.
BACKGROUND
We have previously shown that flavonoids such as luteolin, apigenin and fisetin inhibit interleukin 4 and interleukin 13 production. In this study, we investigated whether luteolin can suppress CD40 ligand expression by basophils.


METHODS
A human basophilic cell line, KU812, was stimulated with A23187 and phorbol myristate acetate (PMA) with or without various concentrations of luteolin or other flavonoids for 12 h, and CD40 ligand expression was analyzed by FACS. The effect of luteolin on CD40 ligand mRNA expression was studied by semiquantitative reverse transcription PCR analysis. In addition, CD40 ligand expression was also measured in purified basophils that had been stimulated for 12 h with A23187 plus PMA with or without various concentrations of luteolin.


RESULTS
CD40 ligand expression by KU812 cells was enhanced noticeably in response to A23187 and even more strikingly augmented by A23187 plus PMA. The expression was significantly suppressed by 10 or 30 microM of luteolin, whereas myricetin failed to inhibit. Reverse transcription PCR analyses demonstrated that luteolin inhibited CD40 ligand mRNA expression by stimulated KU812 cells. Of the six flavonoids examined, luteolin, apigenin, fisetin and quercetin at 30 microM showed a significant inhibitory effect on CD40 ligand expression. The incubation of purified basophils with A23187 plus PMA significantly enhanced CD40 ligand expression, and the presence of luteolin again had an inhibitory effect.


CONCLUSIONS
Luteolin inhibits CD40 ligand expression by activated basophils.
Hirano
Toru
T
Department of Respiratory Medicine, Allergy and Rheumatic Diseases, Osaka University Medical School, Osaka, Japan.
Arimitsu
Junsuke
J
Higa
Shinji
S
Naka
Tetsuji
T
Ogata
Atsushi
A
Shima
Yoshihito
Y
Fujimoto
Minoru
M
Yamadori
Tomoki
T
Ohkawara
Tomoharu
T
Kuwabara
Yusuke
Y
Kawai
Mari
M
Kawase
Ichiro
I
Tanaka
Toshio
T
D047310:Apigenin / Q000494:pharmacology; D001491:Basophils / Q000187:drug effects* / Q000276:immunology; D023201:CD40 Ligand / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D000001:Calcimycin / Q000494:pharmacology; D002460:Cell Line; D005419:Flavonoids / Q000494:pharmacology; D044948:Flavonols; D006801:Humans; D015847:Interleukin-4 / Q000276:immunology; D047311:Luteolin / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D005419:Flavonoids; D044948:Flavonols; D012333:RNA, Messenger; D023201:CD40 Ligand; D015847:Interleukin-4; D000001:Calcimycin; D047310:Apigenin; D047311:Luteolin; D013755:Tetradecanoylphorbol Acetate; C017875:fisetin