Functional studies on platelets of a patient with an acquired disorder of platelet function associated with autoantibodies against membrane glycoprotein IIB/IIIA complex.
Platelet functions have been studied of a 63 year old woman with a severe acquired thrombopathy. The platelets did not adhere to siliconized glass. Aggregation could not be induced by either ADP (1 microM) nor collagen (2 micrograms/ml), no release of serotonin was found under these conditions. Thrombin caused only a weak aggregation response. Quantitative analysis of platelet actin revealed a very low total actin content (473 micrograms/10(9) platelets) and an extremely low F-actin value (3% of total actin). Stimulation of platelets with 0.1 U/ml thrombin for 3 min resulted in an increase of only 5% F-actin, whereas ADP and collagen did not induce any actin polymerization. Ca2+ movement in the patient's platelets is severely impaired after ADP and collagen stimulation, whereas a normal Ca2+ movement was obtained by 0.1 U/ml thrombin. The inhibition of the functions of normal platelets (aggregation and actin polymerization) by addition of patient's serum (5-10% final concentration) points to receptor blockade by platelet autoantibodies in the patient's serum. The antibody was purified by adsorption on Protein-A-Sepharose. Addition of IgG-suspension (5% final concentration) to washed control platelets resulted in similar effects on aggregation and actin polymerization compared to the effects of patient's serum.
Spangenberg
P
P
Institute of Pathological Biochemistry, J.W. Goethe University, Frankfurt/M., F.R.G.
Kirchmaier
C M
CM
Schirmer
A
A
Meyer
M
M
Breddin
H K
HK
D000199:Actins / Q000097:blood; D001323:Autoantibodies / Q000009:adverse effects*; D001791:Blood Platelet Disorders / Q000097:blood* / Q000276:immunology; D001792:Blood Platelets / Q000187:drug effects / Q000276:immunology* / Q000502:physiology; D002118:Calcium / Q000097:blood; D005260:Female; D006801:Humans; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects; D010980:Platelet Membrane Glycoproteins / Q000276:immunology*
D000199:Actins; D001323:Autoantibodies; D010980:Platelet Membrane Glycoproteins; D002118:Calcium