Platelet activation in newborns detected by flow-cytometry.
Platelet function was investigated in full-term infants on the first, the fourth and tenth days of life and compared to normal adult controls. Platelet function was analyzed through a new cytofluorimetric technique with two murine monoclonal antibodies, PAC-1 and anti-GMP-140, directed against two membrane proteins expressed on the activated platelets' surface. The percentage of activated platelets detected with PAC-1 and anti-GMP-140 was evaluated at basal condition and after in vitro stimulation with a weak agonist (ADP) and a strong Txa2 analogue inducer (U 46619). At day 1 platelet activation at basal condition was negligible and similar to adult controls both with PAC-1 (1.2 vs 1.1%) and anti-GMP-140 (2.6 vs. 3.3%). On the contrary, after ADP stimulation the percentage of PAC-1-positive activated platelets was significantly reduced in neonates compared to adults (22 vs. 66%; p < 0.001) and even more after U 46619 (11 vs. 72%; p < 0.001). The percentage of anti-GMP-140-positive activated platelets behaved similarly after adding both ADP (26 vs. 46%; p < 0.01) and U 46619 (37 vs. 67%; p < 0.001). The reduced platelet activation after ADP and U 46619 persisted at day 4 both with PAC-1 and with anti-GMP-140. On the contrary, at day 10 newborn platelets analyzed with anti-GMP-140 behaved similarly to the adult ones both at basal condition and after stimulation with ADP or U 46619 (6 vs. 3% at basal state, 42 vs. 46% after ADP addition, and 55 vs. 67% after U 46619). These data demonstrate that the reduced platelet activation present in newborns is restored by the tenth day after birth.
Gatti
L
L
Centro Trasfusionale e di Immunoematologia, Istituti Clinici di Perfezionamento, Milano, Italia.
Guarneri
D
D
Caccamo
M L
ML
Gianotti
G A
GA
Marini
A
A
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000244:Adenosine Diphosphate / Q000494:pharmacology; D000328:Adult; D000375:Aging; D000911:Antibodies, Monoclonal; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007231:Infant, Newborn / Q000097:blood*; D008297:Male; D015539:Platelet Activation / Q000187:drug effects; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D011450:Prostaglandin Endoperoxides, Synthetic; D013928:Thromboxane A2; D000244:Adenosine Diphosphate; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid