title: Case report: a novel form of free protein S deficiency in an HIV-positive patient on hemodialysis.
abstract: Investigation of repetitive thrombotic episodes in an HIV-positive patient on maintenance hemodialysis revealed extraordinarily high levels of total (free plus protein bound) protein S antigen but severe reductions in free (interactive) protein S antigen. Patients with the nephrotic syndrome or chronic renal failure have shown elevations of total protein S antigen, associated with increased levels of the specific C4b-binding protein, yet have had normal free protein S antigen levels. Based on the fall in total and free protein S levels during hemodialysis treatments, the presence of normal levels of C4b-binding protein, and the coexistence of a polyclonal gammopathy, the authors infer the presence of a unique protein that binds protein S in this patient and that is not apparent in normal plasma. The anomalous association of protein S with this binding protein resulted in levels of free protein S antigen in the range of those reported in hereditary deficiencies of the anticoagulant.
authors.affiliation: Department of Internal Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond.
authors.forename: R M
authors.initials: RM
authors.lastname: Culpepper
authors.forename: M E
authors.initials: ME
authors.lastname: Carr
mesh_terms: D000328:Adult; D001798:Blood Proteins / Q000172:deficiency*; D015433:Glomerulonephritis, Membranous / Q000209:etiology / Q000628:therapy; D006023:Glycoproteins / Q000172:deficiency*; D015658:HIV Infections / Q000097:blood* / Q000150:complications; D006801:Humans; D008297:Male; D017293:Protein S; D006435:Renal Dialysis; D013927:Thrombosis / Q000097:blood* / Q000150:complications / Q000188:drug therapy
chemical_list: D001798:Blood Proteins; D006023:Glycoproteins; D017293:Protein S