What defines acute cellular rejection in a heart transplant patient?

Acute cellular rejection in a heart transplant patient is characterized by histological evidence of lymphocytic infiltration. This type of rejection occurs when the recipient’s immune system recognizes the transplanted heart as foreign and mounts an immune response against it. The presence of lymphocytes, particularly T-cells, infiltrating the myocardial tissue is a hallmark of this process. This infiltration can lead to damage of the cardiac tissue and is typically detected through endomyocardial biopsies, which are a routine part of post-transplant monitoring.

Monitoring for acute cellular rejection is crucial because it can significantly impact graft function. The identification of lymphocytic infiltration also helps clinicians determine the appropriate course of action, including whether adjustments in immunosuppression are necessary.

The other choices do not define acute cellular rejection as clearly as the histological evidence of lymphocytic infiltration does. While the presence of donor-specific antibodies could indicate rejection, it is more associated with acute humoral rejection rather than the cellular type. An increase in immunosuppressive therapy may be needed in response to acute rejection but does not specifically define it. Stable graft function with normal left ventricular ejection fraction (LVEF) would suggest that there is no acute rejection occurring at that moment, contradicting the premise