拒絶反応と考えられたヒト移植角膜片の電子顕微鏡的検討

Ultrastructure of a corneal graft following apparent rejection

　70歳女性が8年前に白内障手術を受け，水庖性角膜症が発症し，3年前に全層角膜移植術を右眼に受けた。その後拒絶反応が生じ，全層角膜移植術が再び行われた。得られた移植片を透過電子顕微鏡で検索した。実質には変性した実質細胞や，アポトーシス小体を貧食するマクロファージが認められ，コラーゲン走行は不規則で空胞変性が認められた。デスメ膜下に厚い角膜後面膜が形成され，内皮細胞は変性，脱落していた。これらの所見は動物実験でみられる角膜拒絶反応と同様であり，そのなかにアポトーシス小体があることから，ヒト角膜拒絶反応にアポトーシスが関与していることが推定された。

A 70-year-old woman had received cataract surgery 8 years before. She had received penetrating kerato-plasty for bullous keratopathy 3 years before. The corneal graft was edematous with signs of graft rejection. She under-went another keratoplasty and the removed corneal graft was examined by transmission electron microscopy. The cor-neal stroma contained degenerated stromal cells and macrophages phagocytising apoptotic bodies. It also showed ir-regular collagen fibrils and vacuolated cells. A thick retrocorneal membrane had formed under Descemet membrane. The endothelial cells had degenerated and were mostly absent. These findings were similar to those observed during corneal rejection in animal experiments. Presence of apoptotic bodies seemed to suggest that apoptosis is involved in corneal rejection in humans.