Summary
Red blood cells (RBC) increase the proaggregatory capacity of a cell-free supernatant
obtained by stimulating platelet-rich plasma (PRP) samples with collagen (1 μg/ml)
as measured by the BASIC wave; this effect increases with the number of RBC and is
proportionally greater with a lower number of platelets or when lower collagen concentrations
are used.
Aspirin (ASA) modifies the RBC behaviour in relation to their platelet-collagen interaction.
This is demonstrated by the fact that when PRP and RBC obtained from the same subjects
before and two hours after the ingestion of ASA (0.5 g) were mixed, it was found that
non-AS A-RBC stimulate ASA-PRP, probably through a platelet cyclooxygenase independent
pathway; ASA-RBC, however, stimulate non-ASA-PRP, but not ASA-PRP, which suggests
that they may need an active platelet cyclooxygenase system for their action. This
effect of ASA on RBC is not transient and was also observable 48 h after ASA ingestion.
In addition, it was found that ASA-RBC greatly increase the activation of a mixture
containing a small proportion of non-ASA-PRP in ASA-PRP, a situation that is expected
to be encountered “in vivo” after ASA treatment. This effect of ASA-RBC on platelet
activation may help to explain the sometimes contradictory clinical effect of aspirin
as an antithrombotic drug.
Key words
Platelet activation - Erythrocytes - Platelet - Erythrocyte interactions - Aspirin
