Ensley R D, Ives M, Zhao L, McMillan M, Shelby J, Barry W H
University of Utah School of Medicine, Salt Lake City 84132.
J Am Coll Cardiol. 1994 Dec;24(7):1769-78. doi: 10.1016/0735-1097(94)90186-4.
This study was performed to determine the mechanisms by which allosensitized lymphocytes cause contractile dysfunction in cultured ventricular myocytes and to compare the effects on isolated myocytes with those observed in an intact heart preparation during allograft rejection.
Allograft rejection may be associated with reversible abnormalities of both systolic and diastolic function. The immunologic mechanisms that cause ventricular dysfunction are poorly understood.
Vascularized heterotopic abdominal heart transplantation was performed in mice. Contractile function of excised allografts undergoing rejection was assessed using a Langendorff perfusion apparatus and a strain gauge. Spontaneously beating monolayers of cultured ventricular myocytes from donor strain fetal mice were exposed to the allosensitized cytotoxic T lymphocytes, and the effects on myocyte motion, intracellular calcium transients, relaxation half-time, membrane potential and myocyte lysis (chromium-51 release) were measured.
In intact hearts, histologically mild rejection without myocyte necrosis was associated with decreased systolic function without slowing of relaxation. In cultured fetal myocytes, sensitized lymphocytes induced a progressive decrease in the amplitudes of myocyte motion and calcium transients, with cessation of beating within 40 min. Also, the diastolic membrane potential and amplitude of the action potential decreased. Relaxation half-time, as estimated by measurement of cell motion, was unchanged. The effect was allospecific and was reversible with early removal of lymphocytes from the myocyte monolayer. Pretreatment of lymphocytes with the degranulation inhibitor 4,4'-diisothiocyano-2,2'-disulfonic acid stilbene blocked both the negative inotropic effect and myocyte lysis.
We conclude that impaired relaxation is not a prominent feature of contractile dysfunction caused directly in myocytes by alloimmune injury from cytotoxic lymphocytes. Allosensitized lymphocytes can cause reversible systolic dysfunction in myocytes by means of a direct cell-cell interaction. This effect may be in part responsible for the reversible systolic dysfunction associated with allograft rejection.
本研究旨在确定同种异体致敏淋巴细胞导致培养的心室肌细胞收缩功能障碍的机制，并比较其对分离的心肌细胞的影响与在同种异体移植排斥反应期间在完整心脏制剂中观察到的影响。
同种异体移植排斥反应可能与收缩和舒张功能的可逆性异常有关。导致心室功能障碍的免疫机制尚不清楚。
在小鼠中进行血管化异位腹部心脏移植。使用Langendorff灌注装置和应变仪评估正在发生排斥反应的切除同种异体移植物的收缩功能。将来自供体品系胎鼠的培养心室肌细胞的自发跳动单层暴露于同种异体致敏的细胞毒性T淋巴细胞，并测量其对心肌细胞运动、细胞内钙瞬变、舒张半衰期、膜电位和心肌细胞溶解（铬-51释放）的影响。
在完整心脏中，组织学上轻度排斥反应且无心肌细胞坏死与收缩功能降低有关，但舒张并未减慢。在培养的胎儿心肌细胞中，致敏淋巴细胞导致心肌细胞运动和钙瞬变幅度逐渐降低，在40分钟内停止跳动。此外，舒张膜电位和动作电位幅度降低。通过测量细胞运动估计的舒张半衰期未改变。这种作用是同种异体特异性的，并且通过早期从心肌细胞单层中去除淋巴细胞是可逆的。用脱颗粒抑制剂4,4'-二异硫氰基-2,2'-二磺酸芪预处理淋巴细胞可阻断负性肌力作用和心肌细胞溶解。
我们得出结论，舒张功能受损不是细胞毒性淋巴细胞的同种异体免疫损伤直接在心肌细胞中引起的收缩功能障碍的突出特征。同种异体致敏淋巴细胞可通过直接的细胞间相互作用导致心肌细胞可逆的收缩功能障碍。这种作用可能部分导致了与同种异体移植排斥反应相关的可逆性收缩功能障碍。
