1. ¹West China School of Preclinical and Forensic Medicine, Sichuan University, Sichuan, People's Republic of China
2. ²State Key Laboratory of Biotherapy of Human Diseases, West China Medical School, Sichuan University, Sichuan, People's Republic of China

Correspondence: Dr L Zhang, West China School of Preclinical and Forensic Medicine, Sichuan University, Number 17, Section 3, Renmin Nan Road, Chengdu, Sichuan 610041, People's Republic of China. E-mail: kjc@scu.edu.cn

Received 24 November 2006; Revised 20 April 2006; Accepted 20 April 2006; Published online 18 May 2006.

Abstract

Experimental autoimmune encephalomyelitis (EAE) is a T-cell-mediated autoimmune disease. Chemokine receptor CCR5 has been shown to be essential for the T-cell recruitment to the inflammatory site in EAE. In this study, we assumed that an immunotoxin directed at CCR5⁺ cells would be able to reduce the disease activity of EAE. A recombinant immunotoxin, DT390-RANTES-SR, was constructed in an eukaryotic cell expression plasmid consisting of regulated on activation normal T cells expressed and secreted (RANTES) as the targeting moiety and DT390 as the toxic moiety. DT390-RANTES was expressed in vitro and was highly toxic to activated mouse T cells with the inhibitory concentration 50 at 0.18 ng/ml. To evaluate whether DT390-RANTES was effective in preventing EAE, C57BL/6 mice were immunized with myelin basic protein, emulsified with complete Freund's adjuvant and were treated by injecting cationic liposome-embedded plasmid DNA into the muscle of hind limbs. Mice treated with DT390-RANTES-SR developed a much milder EAE compared to mice treated with phosphate-buffered saline or the empty plasmid DNA. Much less CCR5⁺-infiltrating cells were found in the central nervous system in DT390-RANTES-SR-treated mice than in the control mice. This study indicates that recombinant immunotoxin can be expressed in vivo, and targeting CCR5 can attenuate the disease activity of EAE in mice.