Platelet aggregation, platelet TNF-α receptor expression, and plasma TNF-α in HSs and HF patients.(A) Collagen-induced platelet aggregation (PA) and serumTxB₂ production in patients with mild and severe HF (^*P < .001 severe vs mild HF) and in HSs (§P < .001). (B) TNF-α plasma levels in patients with mild and severe HF (^*P < .001 vs HSs; ^§P < .001 vs mild HF). (C) TNFR1 and TNFR2 expression on platelet surfaces in patients with mild HF (n = 10; 9 men, 1 woman; age, 58 ± 10 years) and severe HF (n = 10; 9 men, 1 woman; age, 58 ± 6 years) and in HSs (n = 10; 9 men, 1 woman; age, 58 ± 7 years) (^*P < .001 vs HSs; ^§P < .001 vs mild HF). (D) Correlation between platelet TNFR1 and PA (r = 0.79; P < .001) in 20 patients with HF and 10 HSs. (E) Collagen-induced PA in aspirin-free patients with mild (n = 10) or severe (n = 10) HF and in HSs (n = 10) in the presence or absence of the TNFR inhibitor WP9QY (^*P < .01; ^**P < .001) (F) Effect of WP9QY or AACOCF₃ or acetylsalicylic acid (ASA) on TNF-α-induced activation of collagen (0.5 μg/mL)-primed platelets taken from 3 patients with mild HF and 2 patients with severe HF (^§P < .001 vs TNF-α-free platelets; ^*P < .001 vs platelets added with collagen and TNF-α). Data (n = 5) are expressed as mean ± SD.