IV型コラーゲンは基底膜の主要構成成分であり,生体内に広く分布している.移植後急性期腎機能低下例においては,腎臓のIV型コラーゲン分布に変化が認められる.今回我々は移植腎機能廃絶の主原因である慢性期移植腎機能低下症(chronic allograft nephropathy: CAN)におけるIV型コラーゲンの変化について検討した.当院において施行された腎移植患者を,移植腎機能に基づいて以下の群に分類し,組織所見について検討した.なおCAN症例は,光学顕微鏡所見で診断された症例を用いた.Group A(n=5):腎機能正常群,Group B(n=10):急性期移植腎機能低下群,Group C(n=35): CAN症例で血清クレアチニン値2～4mg/dl,Group D(n=15): CANで血清クレアチニン値>4mg/dl.各症例におけるIV型コラーゲン分布について,IV型コラーゲンのα1鎖に対するモノクローナル抗体であるJK199,JK132を用いて,蛍光顕微鏡により検討した.Group AではJK199,JK132ともにメサンギウム基質(MM),ボーマン嚢基底膜(BBM),尿細管基底膜(TBM)に対する反応のみを認めた.Group Bでは,JK199はMM,BBM,TBMに加え,糸球体基底膜(GBM)および腎間質(INS)に対する反応を認めた.JK132の反応性はGroup Aと同様であった.一方,Group CおよびGroup Dでは,JK199においてはMM,GBM,BBM,TBM,INSに対する反応性が増強していた.JK132についてはMM,BBM,TBMに加え,GBMおよびINSにおいても反応が認められた.また,JK199およびJK132の反応性はGroup CよりもGroup Dにおいて強い傾向が認められた.GBMおよびINSにおけるJK132の反応陽性化はCANに特異的な所見であることが示唆された.Previously, we demonstrated the altered formation of collagen IV, which is the main constituent of the basement membrane, in renal allografts by staining with two monoclonal antibodies against the α1 chain of collagen IV. In the present study, we investigated the alteration of collagen IV in chronic allograft nephropathy (CAN), which is an irreversible change that can occur in renal allografts. Biopsy specimens of normal kidneys (Group A: n=5) and acute rejection (Group B: n=10) were studied as controls. Fifty biopsy specimens from 41 patients who had been diagnosed as having CAN were divided into two groups, according to renal function: Group C (n=35), sCr 2～4 mg/dl, and Group D (n=15), sCr>4 mg/dl. Two monoclonal antibodies, JK199 and JK132, those recognize the α1 chain of collagen IV were used. In Group A, JK199 reacted with the glomerular basement membrane (GBM), the mesangial matrix (MM), the basement membrane of Bowman's capsule (BBM) and the tubular basement membrane (TBM). JK132 only reacted with the MM, BBM and TBM. In Group B, JK199 reacted with GBM, MM, BBM, TBM and the interstitium (INS). JK132 only reacted with MM, BBM and TBM. In Group C and Group D, JK199 and JK132 reacted universally with GBM and INS in addition to MM, BBM and TBM. The intensity of the reaction was higher in Group D than in Group C. Thus, the reactivity of JK132 with GBM and INS was a unique finding for the CAN specimens. These results suggest that collagen IV is upregulated in CAN and the reactivity of JK132 in GBM and INS may represent the point of irreversible dysfunction of renal allografts
