title: Suppressed natural killer cell activity in patients with chronic autoimmune thrombocytopenic purpura.
abstract: Natural killer (NK) cell activity was studied in 17 patients with primary chronic idiopathic autoimmune thrombocytopenic purpura (ATP). Fifteen of 17 patients had a significantly reduced NK cytotoxicity against 51chromium labeled K562 target cells (mean LU20% = 18 +/- 20 in patients versus 65 +/- 25 in controls, P less than 0.001). NK activity was also significantly reduced in all of six patients with secondary ATP as compared with normal controls (LU20% 28 +/- 15, respectively, P less than 0.005). The NK activity in both patient groups correlated with the duration of therapy being received (r = 0.60, P less than 0.001). Immunophenotypic analysis of peripheral blood mononuclear cells from patients with ATP revealed that CD8- cells bearing CD57 (HNK-1, Leu 7) and CD3- cells bearing CD56 (Leu 19) were quantitatively within the normal range. These findings indicate that patients with ATP have a functional defect in NK cytolytic activity.
authors.affiliation: Department of Immunohematology, St. Michael's Hospital, Toronto, Ontario, Canada.
authors.forename: J W
authors.initials: JW
authors.lastname: Semple
authors.forename: S
authors.initials: S
authors.lastname: Bruce
authors.forename: J
authors.initials: J
authors.lastname: Freedman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001327:Autoimmune Diseases / Q000150:complications / Q000276:immunology* / Q000473:pathology; D002908:Chronic Disease; D005260:Female; D006801:Humans; D007108:Immune Tolerance; D007694:Killer Cells, Natural / Q000276:immunology*; D016131:Lymphocyte Subsets / Q000166:cytology; D008297:Male; D008875:Middle Aged; D011696:Purpura, Thrombocytopenic / Q000150:complications / Q000276:immunology* / Q000473:pathology