Transfer of T antigen from ICH virus-induced hamster tumor cells to dog kidney cells by cell fusion technique (Department of Animal Husbandry)

ICHウイルス誘発ハムスター腫瘍よりin vitroで確立したHT-7細胞とイヌ腎由来の株化細胞MDCKをUV不活化HVJの仲介のもとに細胞融合を起させ, HT-7細胞の有するT抗原をMDCKに移行させるべく, 実験を試みた。その結果, 細胞融合により約10∿30%のホモあるいはヘテロカリオンが形成されたが, 多核体のヘテロカリオン中に螢光抗体法によってT抗原を有するMDCKの核がみられ, イヌ細胞へのT抗原の移行を確認できた。なお, 細胞融合によってICHウイルスの活性化はできなかったが, 一部のMDCKの核に, ICHウイルス増殖の過程でみられる核内封入体と類似のものが観察され, このものはT抗体によって染色された。融合細胞を7∿10代継代後, その100∿500万個を生後96時間以内の仔イヌの皮下に移植を行ない, 腫瘍の発現の可能性を検討した。その結果, 細胞移植後1∿2週の間に局所に小指頭大∿拇指頭大の腫瘤の発生があり, その大きさはHVJ仲介のもとで融合させた細胞を移植されたイヌで著明であった。しかし, 腫瘤の病理組織学的観察結果は, 移植細胞の増殖によるものでなく, それをとりまく生体側の肉芽腫形成と診断され, 細胞融合法によってT抗原産生能を獲得したと思われるMDCKによる腫瘍の発現は確認し得なかった。Attempts to transfer T antigen from HT-7 cells originated from ICH virusinduced hamster tumor to established dog kidney cells (MDCK) were carried out using cell fusion technique. The percentage of multinucleated homo- and hetero-karyons produced after fusion of the both cell types in the presence of inactivated HVJ was approximately 10-30%. When heterokaryon cultures were examined for presence of T antigen by immunofluorescent staining, some multinucleated cells contained fluorescing nuclei being of MDCK origin. The fact seems to indicate that transfer of T antigen from the HT-7 cells to MDCK took place. Attempts to reactivate ICH virus from the HT-7 cells by fusion technique were unsuccessful, but in some nuclei of MDCK origin, inclusion body-like structure resembling that of ICH virus-infected MDCK was observed. The structure was shown to contain T antigen by immunofluorescent staining. To determine whether the MDCK thus treated can produce tumor in dogs, the fused cells after being passaged for 7 to 10 times were inoculated subcutaneously into baby dogs less than 96 hours of age. Within 2 weeks after inoculation, palpable mass at site of inoculation was noted in some of the dogs but was regressed gradually thereafter. On histological examination, the mass was designated granulom. Tumor development could not be confirmed by such methods