FcgammaRIIB Gene Research Articles

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.

Genomic organization of mouse Fc gamma receptor genes.

We have isolated and characterized the gene coding for the mouse Fc receptor that is termed Fc gamma RIIa. The gene contains five exons and spans approximately 9 kilobases. Unlike most members of the immunoglobulin gene superfamily, this gene utilizes multiple exons to encode its leader peptide. The first exon encodes the hydrophobic region of the signal sequence; the second exon, which contains only 21 base pairs, encodes a segment of the signal peptidase recognition site; and the beginning of the third exon encodes the predicted site of peptidase cleavage. The third and fourth exons each code for immunoglobulin-like extracellular domains. The fifth exon encodes the hydrophobic transmembrane domain and the cytoplasmic tail. Partial characterization of the Fc gamma RIIb gene indicates that it also contains multiple leader exons, including a 21-base-pair exon and two exons coding for homologous immunoglobulin-like extracellular domains. However, the Fc gamma RIIb gene uses four exons to encode its intracytoplasmic region. Analysis using contour-clamped homogeneous electric field (CHEF) gels indicates that the Fc gamma RIIa and Fc gamma RIIb genes are linked within 160 kilobases on mouse chromosome 1.