AGTR1 and connective tissue disorder: Aim of the present study was, therefore, to determine the occurrence of functionally active anti-AT1R antibodies in SSc and other connective tissue disorders by a newly developed luminometric assay using Chinese hamster ovary (CHO-K1) cells transfected with the AT1R plasmid DNA thus overexpressing the receptor but also a human cell line, Huh7, known to constitutively express AT1R. This assay was compared with commercially available ELISA for the detection of anti-AT1R antibodies but also with the presence of anti-topo-I antibodies.