Tea polyphenol inhibits allostimulation in mixed lymphocyte culture.
Green tea polyphenols are known to protect allogenic donor tissues from acute rejection by their recipients. This immunosuppressive effect may be generated by a unique chemical property of the major component, epigallocatechin-o-gallate (EGCG), which can block specific cell surface molecules of the donor tissues. To test this hypothesis, we examined the effects of EGCG on the murine mixed lymphocyte reactions. EGCG treatment of stimulator cells significantly attenuated the proliferation of responder T cells. The proliferation did not recover upon the secondary stimulations by fresh untreated cells or exogenous IL-2. Flow cytometric analyses showed that EGCG treatment decreased the staining intensities of various cell surface molecules including MHC II, which plays a major role in antigen presentation, and B7.1, B7.2, and their ligand, CD28, which are required for costimulatory signals in T-cell activation. These results suggest that an anergic state of alloreactive T cells may be induced by either weakening of antigen signaling or blockage of costimulatory signals with EGCG. Other possible mechanisms behind the immunosuppressive effect and a potential use of EGCG treatment of donor tissues in transplantation medicine are discussed.
Kim
Jong-yoon
JY
Department of Simulation Medical Engineering, Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan.
Kina
Tatsuo
T
Iwanaga
Yasuhiro
Y
Noguchi
Hirofumi
H
Matsumura
Kazuaki
K
Hyon
Suong-hyu
SH
D000818:Animals; D017209:Apoptosis; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D049109:Cell Proliferation; D002478:Cells, Cultured; D005260:Female; D005419:Flavonoids / Q000494:pharmacology; D005434:Flow Cytometry; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007376:Interleukin-2 / Q000276:immunology; D008213:Lymphocyte Activation / Q000187:drug effects*; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010636:Phenols / Q000494:pharmacology; D010936:Plant Extracts / Q000737:chemistry; D059808:Polyphenols; D013662:Tea / Q000737:chemistry
D005419:Flavonoids; D007166:Immunosuppressive Agents; D007376:Interleukin-2; D010636:Phenols; D010936:Plant Extracts; D059808:Polyphenols; D013662:Tea; D002392:Catechin; C045651:epigallocatechin gallate