Acute Cellular Rejection -
Working Formulation

Grading of acute cellular rejection. Historically, several methods to assess the histologic grade of rejection have been used by different transplant centers. But in 1990, the International Society for Heart and Lung Tranasplantation (ISHLT ) published a standardized international grading system for the purpose of effectively communicating outcomes in multicenter drug trials and among institutions using different treatment regimens. This was envisioned as a working formulation (WF1990). This working formulation was in use until 2004 when it was updated by the ISHLT. The table below shows the two working formulations.  

 

Working Forumulation ISHLT 1990	Working Forulation ISHLT 2004
Grade 0 (No Acute Rejection)	Grade 0R (No Acute Cellular Rejection)
Grade 1A (Focal, Mild Acute Rejection)	Grade 1R (Mild, Low-grade, Acute Cellular Rejection) - Interstitial and/or peri-  vascular infiltrate with up to 1 focus of myocyte damage
Grade 1B (Diffuse, Mild Acute Rejection)
Grade 2 (Focal, Moderate Acute Rejection)
Grade 3A (Multifocal Moderate Rejection)	Grade 2R (Moderate, Intermediate-grade, Acute Cellular Rejection) - Two or more foci of infiltrate with associated myocyte damage
Grade 3B (Diffuse, Borderline Severe Acute Rejection)	Grade 3R (Severe, High-grade, Acute Cellular Rejection) - Diffuse infiltrate with multifocal myocyte damage ± edema, ± hemorrhage ± vasculitis
Grade 4 (Severe Acute Rejection)

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