Dendritic cells co-localize with activated CD4+ T cells in giant cell arteritis.

Abstract

The immediate co-localization of dendritic cells and activated T cells indicate a high probability that the former represent the antigen presenting cells in GCA. In addition, because of the presence of Rho A and Rac1 in the granulomatous infiltrates, we speculate that they provide the right environment for cell-cell contact and adhesion, and that they may promote the internalization of bacteria. TNF alpha is expressed at high levels in the granulomatous infiltrates of temporal artery specimens from patients with GCA. Since TLR4 is produced in the same cell types, and predominantly in the adventitial layer of the temporal artery, we suggest that these receptors are coupled to signal transduction pathways that control TNF alpha expression.