The monoclonal antibody clone AS02 reacts specifically with human CD90 (Thy-1), a GPI-anchored glycoprotein of the immunoglobulin superfamily with a molecular weight of 25 – 35 kDa.
CD90 (Thy-1) in human is primarily expressed by nerve cells, additionally in a sub-population (20%) of CD34+ blood stem cells and in various fibroblasts. In contrast to mouse and rat it is not expressed by thymocytes and peripheral blood T cells. AS02 recognizes fibroblasts of different origin but does not react with human blood cells, keratinocytes, resting micro-/macrovascular endothelial cells and components of the extracellular matrix like fibronectin, collagen type I, III, IV and laminin. Thus, AS02 is especially suitable for the specific detection and cell separation of human fibroblasts. Activated endothelial cells, after stimulation in vitro or in tissue sec-tions of inflamed tissue in vivo, bind AS02 with different intensities, implying that CD90 (Thy-1) can be considered to be an activation marker of human endothelial cells. Recent papers demonstrate the binding of AS02 with activated microvascular endothelial cells, with a subpopulation of lung fibroblasts, specialized lymph node fibroblasts, but not lymphocytes and normal or inflamed synovial fibroblasts in human.
In immunoblot analysis AS02 detects nonreduced CD90 at 30 kDa.