[Determination of the ADAMTS13 antigen and its activity in TTP patients and carriers].
OBJECTIVE
To investigate the antigen levels and activity of von Willebrand factor cleaving protease ADAMTS13 in thrombotic thrombocytopenic purpura (TTP) patients and carriers.


METHODS
28 samples from 13 TTP patients and 10 samples from the carriers were examined. The activity of ADAMTS13 was measured by residue collagen binding assay, and antigen by a newly developed sandwich ELISA.


RESULTS
The mean ADAMTS13 level in Chinese normal controls (CN) was (600.93 +/- 145.36) mU/ml (n = 26) comparable to the level (1000 mU/ml) in pooled normal Caucasian plasma, and the activity was (74.79 +/- 11.81)%. Both the antigen level and activity of ADAMTS13 in congenital TTP patients either before plasma exchange (pre-PE) or interval relapse were quite lower than those in normal control, but were increased after PE (post-PE). The antigen was (331.40 +/- 109.85) mU/ml (P < 0.01, n = 10), and activity was (66.79 +/- 12.82)% (P > 0.05). The ADAMTS13 levels pre-PE in idiopathic TTP was (98.7 +/- 82.08) mU/ml (n = 11, P < 0.01), and that post-PE was up to (449.4 +/- 232.33) mU/ml (P < 0.01, n = 10). The activity of ADAMTS13 in patients pre-PE and post-PE were (22.23 +/- 19.07)% (P < 0.01) and (60.92 +/- 22.33)% (P > 0.05) respectively. In a secondary TTP patient the ADAMTS13 antigen was much higher than that in CN, and the activity was 6.00%.


CONCLUSIONS
The antigen and activity of ADAMTS13 in most TTP patients pre-PE are deficient, and these two indices in most TTP patients are paralleled. The reason for ADAMTS13 deficiency is congenital shortage or clearance by immune system, but it is unknown that why in some patients the ADAMTS13 antigen is extremely high but its activity is quite low.
Liu
Fang
F
Jiangsu Institute of Hematology, First Affiliated Hospital of Soochow University, Suzhou 215006, China.
Feys
Hendrik B
HB
Dong
Ning-zheng
NZ
Bai
Xia
X
Vanhoorelbeke
Karen
K
Deckmyn
Hans
H
Ruan
Chang-geng
CG
D051722:ADAM Proteins / Q000097:blood* / Q000276:immunology; D000071120:ADAMTS13 Protein; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D011697:Purpura, Thrombotic Thrombocytopenic / Q000097:blood* / Q000276:immunology
D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human