Plasma from patients with idiopathic and human immunodeficiency virus-associated thrombotic thrombocytopenic purpura induces apoptosis in microvascular endothelial cells.
The pathogenesis of thrombotic thrombocytopenic purpura (TTP) is obscure. It is manifested classically by platelet thrombi and localized microvascular endothelial cell (EC) proliferation, in the absence of an inflammatory response. It is statistically associated with human retroviral disease, but pathological studies of TTP lesions have been unable to establish whether perturbation of the endothelium is a primary or secondary event, irrespective of the presence of retroviral infection. We document that plasma from all of four acute TTP patients, with or without human immunodeficiency virus infection, can induce apoptosis in cultured ECs of microvascular but not large vessel origin. This process was documented by three different methods, (1) laser-illuminated light scatter, (2) quantitation of the pre-G1 Ao peak on DNA histograms and direct visualization of chromatin fragmentation by acridine orange and 4'6-diamidino-2-phenylindole staining, and (3) agarose gel electrophoresis of low molecular weight cellular DNA. Apoptosis was independent of tumor necrosis factor-alpha secretion or the presence of CD36 on microvascular ECs but was linked to the rapid induction of Fas (CD95) on these cells. Soluble anti-Fas antibody, normal plasma depleted of cryoprecipitate, and low concentrations (< or = 0.1 micromol/L) of aurintricarboxylic acid were capable of suppressing TPP plasma-mediated EC apoptosis. In conclusion, microvascular EC apoptosis may be of pathophysiological importance in TTP may be susceptible to interruption by blockade of initiating signals for, or final common enzyme pathways leading to, programmed cell death.
Laurence
J
J
Laboratory for AIDS Virus Research,Department of Medicine, Cornell University Medical College, New York 10021, USA.
Mitra
D
D
Steiner
M
M
Staiano-Coico
L
L
Jaffe
E
E
D000165:Acridine Orange; D017209:Apoptosis / Q000187:drug effects*; D001483:Base Sequence; D018955:CD36 Antigens / Q000032:analysis; D002196:Capillaries / Q000166:cytology*; D002843:Chromatin / Q000648:ultrastructure; D004249:DNA Damage; D004587:Electrophoresis, Agar Gel; D004730:Endothelium, Vascular / Q000187:drug effects*; D053222:Fas Ligand Protein; D005456:Fluorescent Dyes; D015658:HIV Infections / Q000097:blood / Q000150:complications*; D006801:Humans; D007211:Indoles; D008562:Membrane Glycoproteins / Q000032:analysis; D008969:Molecular Sequence Data; D009391:Nephelometry and Turbidimetry; D009928:Organ Specificity; D011697:Purpura, Thrombotic Thrombocytopenic / Q000097:blood* / Q000209:etiology; D012867:Skin / Q000098:blood supply; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014471:Umbilical Veins / Q000166:cytology; D019014:fas Receptor / Q000032:analysis
D018955:CD36 Antigens; D002843:Chromatin; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D005456:Fluorescent Dyes; D007211:Indoles; D008562:Membrane Glycoproteins; D014409:Tumor Necrosis Factor-alpha; D019014:fas Receptor; C007293:DAPI; D000165:Acridine Orange