Expression of human tumor-associated antigen RCAS1 in Reed-Sternberg cells in association with Epstein-Barr virus infection: A potential mechanism of immune evasion

✍ Scribed by Koichi Ohshima; Koichiro Muta; Manabu Nakashima; Seiji Haraoka; Takeshi Tutiya; Junji Suzumiya; Chika Kawasaki; Takeshi Watanabe; Masahiro Kikuchi

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: French
• Weight: 226 KB
• Volume: 93
• Category: Article
• ISSN: 0020-7136
• DOI: 10.1002/ijc.1300

✦ Synopsis

RCAS1 (receptor-binding cancer antigen expressed on SiSo cells) is present in neoplastic cells, induces apoptosis of natural killer (NK)/T cells and plays a role in immune evasion. Fas ligand (FasL) is considered to have similar roles. The Epstein-Barr virus (EBV)-encoded latent membrane protein is expressed by malignant Hodgkin and Reed-Sternberg (H&RS) cells of EBV-associated Hodgkin's disease (HD) and considered to be a target of cytotoxic T lymphocytes (CTLs).

However, CTL response is inadequate in HD. To determine whether RCAS1 and FasL are expressed in EBV-associated HD and participate in immune evasion, tissues of 20 EBV - and 15 EBV ؉ HD cases were immunohistochemically stained for RCAS1, FasL and HLA classes I and II, whose deficiencies could explain CTL escape. Lymphocytes surrounding H&RS cells tended to be CD4 ؉ cells and rarely CD8 ؉ , TIA-1 ؉ (cytotoxic marker) or NK cells. HLA class I and/or II were expressed in all EBV ؉ HD cases, and RCAS1-expressing H&RS cells were found in 14/15 (93%) EBV ؉ HD cases but only 8/20 (40%) EBV -HD cases (p < 0.05). FasL was detected in 9/15 (60%) and 7/20 (35%) EBV ؉ and EBV -HD cases, respectively. ssDNA-positive (apoptotic) lymphocytes, surrounding H&RS cells, were rarely seen but were present in RCAS1 ؉ cases (20/22 cases, 91%) rather than negative cases (0/13 cases, 0%) (p < 0.005). Our findings suggest that EBV ؉ H&RS cells might evade the host immune response by expressing RCAS1 rather than FasL.