CBL415 Sigma-AldrichAnti-Thy-1 Antibody, clone F15-42-1

Progressive renal disease is frequently accompanied by renal interstitial inflammation and fibrosis in which the activity of resident fibroblasts may be of central importance. Because there are relatively few fibroblasts in the normal cortical interstitium and there is no specific marker to permit their identification, these cells have proved difficult to characterize in vitro. In this study, these cells were isolated and established in culture, using CD90 as a positive selection marker. Antibodies to CD90 bound to tubular epithelial cells and fibroblasts, but not to glomerular cells in kidney sections. In culture, only fibroblasts were CD90-positive. These normal renal cortical fibroblasts (RCF) were alpha-smooth muscle actin- and vimentin-positive, but desmin-, cytokeratin-, and factor VIII-negative, identifying them as myofibroblasts. They expressed platelet-derived growth factor alpha and beta receptors; CD44; and alpha 2, beta 1, and beta 3 integrin chains: this combination of markers was also characteristic of fibroblasts in sections of normal cortex. These cells were positive for ICAM-1 but negative for VCAM-1. Similarly, proliferating or growth-arrested renal cortical fibroblasts (RCF) in culture expressed ICAM-1 but not VCAM-1. The expression of VCAM-1 was detected, however, and that of ICAM-1 was increased on fibroblasts associated with inflammatory infiltrates in sections from fibrotic kidneys, and ICAM-1 and VCAM-1 were up-regulated on RCF in culture after incubation with increasing doses of interleukin-1 beta or tumor necrosis factor alpha (maximum between 24 and 48 h). These adhesion molecules were functional, and neutrophils adhered to resting and cytokine-activated RCF. Binding was maximal between 24 and 48 h after cytokine treatment and was inhibited by anti-CD18 antibodies. ICAM-1 is the principal adhesion molecule controlling inflammatory cell infiltration of the interstitium. The study presented here suggests that cortical fibroblasts may be central to the control of this infiltration.

A monoclonal antibody to human Thy-1 has been used to study the anatomical localization of Thy-1 in human brain and to quantitate the relative amounts of Thy-1 in different brain subregions. Quantitative absorption analyses using homogenates of carefully dissected brain subregions, together with an [125I]anti-immunoglobulin binding assay using brain homogenate as target, established that Thy-1 was present in large amounts throughout human brain, but the grey matter of cerebrum (cortical grey matter, caudate nucleus, putamen and thalamus) had 5-10 times as much Thy-1 as white matter. Grey matter of cerebellum (cerebellar cortex and dentate nucleus) also had higher amounts of Thy-1 than white matter, but the total amount of Thy-1 in cerebellum was less than in the cerebrum. Immunofluorescence studies gave interesting results and demonstrated in particular: (a) the outlining of some neuronal cell bodies and their processes (particularly the Purkinje cells of the cerebellar cortex) by spots of fluorescence; (b) staining of what appeared to be cell bodies of satellite cells in areas of grey matter; (c) granular staining in grey but not white matter; (d) staining of what appeared to be fibre tracts in the basal ganglia and thalamus, the tracts appearing duller than the surrounding grey matter of the nuclei; (e) staining of only some fibres in sciatic nerve; and (f) absence of staining of the adrenal gland.