Author + information
- Received October 12, 1993
- Revision received June 6, 1994
- Accepted June 30, 1994
- Published online December 1, 1994.
- R.Douglas Ensley, MD,
- Martha Ives, MD,
- Liping Zhao, MS,
- Mischelle McMillan, MD,
- Jane Shelby, PhD and
- William H. Barry, MD, FACC∗
- ↵∗Address correspondence to: Dr. William H. Barry, Division of Cardiology 4A100, University of Utah Medical Center, 50 North Medical Drive, Salt Lake City, Utah 84132.
Objectives. 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.
Background. Allograft rejection may be associated with reversible abnormalities of both systolic and diastolic function. The immunologic mechanisms that cause ventricular dysfunction are poorly understood.
Methods. 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 allosensitizcd 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.
Results. 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.
Conclusions. 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.
☆ This study was supported in part by Grant ROI HL 42535 from the National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, and by Grant 90-049-010 from the Utah Affiliate of the American Heart Association.
- Received October 12, 1993.
- Revision received June 6, 1994.
- Accepted June 30, 1994.