1. Department of Immunology and Parasitology; Yamagata University School of Medicine; Yamagata Yamagata 990-23 Japan
2. Japan Immunoresearch Laboratories; Takasaki Gunma 370 Japan
3. Department of Biochemistry; Fukuoka University School of Medicine; Fukuoka Fukuoka 814-80 Japan
4. Department of Clinical and Laboratory Medicine; Akita University School of Medicine; Akita Akita 010 Japan