Presence of CD16 on endothelial cells in heart transplant rejection: an immunohistochemical study.

We studied the distribution of Fc gamma RIII (CD16) in human lymphoid and non-lymphoid tissue by immunohistochemistry and two-colour immunofluorescence. In all tissues except stomach, skin, muscle and heart, infiltrating cells were stained. In tonsil and thymus, the CD16 antibody CLBgran 1 labelled some cells with high endothelial morphology in T-cell areas. Two-colour fluorescence combination of CD16 and antibody to Von Willebrand factor confirmed the endothelial nature of the CLB gran 1-positive cells. Fc gamma RIII expression was also demonstrated by antibody CLBgran11, which detects a product of the Fc gamma RIII-B gene of only the NA1 haplotype. A series of 95 endomyocardial biopsies (EMB) taken after heart transplantation was evaluated for Fc gamma RIII expression. In 18 cases Fc gamma RIII was unambiguously detected on endothelial cells by CD16 antibody CLBgran1. There was a significant correlation between capillary CD16 expression and transplant rejection. We conclude that Fc gamma R expression on endothelium represents endothelial activation found in immunopathological and inflammatory conditions.