CARDIAC REJECTION Differential Expression of RANTES Chemokine, TGF-, and Leukocyte Phenotype in Acute Cellular Rejection and Quilty B Lesions Paul J. Michaels, BS, a Jon Kobashigawa, MD, b Hillel Laks, MD, c Amir Azarbal, a Maria L. Espejo, BA, c Leslie Chen, a and Michael C. Fishbein, MD a Background: Because of the complexity of the trabeculated endocardial surface and tangential histologic sectioning, the differentiation of acute cellular rejection (ACR) from Quilty B lesions (QB) in endomyocardial biopsies (EMBs) is problematic. We hypothesized that the phenotype chemokine RANTES (regulated upon activation, normal T cell expressed and secreted) expression of infiltrating cells and the pattern of expression of transforming growth factor– (TGF-) may distinguish ACR from QB. In previous studies, the number of RANTES-positive cells and the expression of TGF- correlated with the severity of rejection. Methods: We used immunohistochemical techniques to stain sections of human EMBs with only QB (n = 14) or with only ACR (International Society for Heart and Lung Transplantation Grades 1A and 1B, n = 7; Grades 3A and 3B, n = 7) for B (CD20) and T-lymphocytes (CD3), macrophages (CD68), RANTES, and TGF- expression. We graded the percentage of positive cells from 0 to 4 (1 = 1% to 25%; 2 = 26% to 50%; 3 = 51% to 75%, and 4 = 76% to 100%). Results: When ACR was compared with QB, we found no difference in the proportion of myocardial B cells (0.9  0.3 vs 1.1  0.3, p = 0.17); however, we found a lesser proportion of T cells (1.8  0.5 vs 2.8  0.9, p 0.01) but more macrophages (2.9  0.5 vs 1.1  0.6, p  0.0001) in ACR than in QB. We also found more RANTES- positive leukocytes in ACR vs QB (2.8  1.3 vs 1.9  0.9, p = 0.03). In QB, many endocardial vessels stained for TGF- (2.9  1.6). Myocardial vessels and injured myocytes in both ACR and QB expressed TGF-. Conclusions: In ACR, although T-lymphocytes are numerous, more than 50% of infiltrating cells are macrophages and more than 50% express RANTES. In QB lesions, more than 50% of infiltrating cells are T-lymphocytes and less that 50% of leukocytes will express RANTES. B cells are present in both ACR and QB, but on average comprise only 25% of the cells present. Thus, a relatively simple immunohistochemical From the Divisions of Anatomic Pathology, a Cardiology, b and Cardiothoracic Surgery, c University of California at Los Ange- les, Los Angeles, California. Submitted March 28, 2000; accepted November 11, 2000. Reprint requests: Michael C. Fishbein, MD, University of Cali- fornia, Los Angeles, Department of Pathology and Laboratory Medicine, 10833 Le Conte Ave., A2-179 CHS, Los Angeles, California 90095-1732. Telephone: 310 825-9731. Fax: 310 794-4161. E-mail: mfishbein@mednet.ucla.edu. Copyright © 2001 by the International Society for Heart and Lung Transplantation. 1053-2498/01/$–see front matter PII S1053-2498(00)00318-1 407