Small EVs were investigated.↑ levels of sEVs in plasma of APS pts. vs. HBD.Platelet (CD41b+, CD42a+), lymphocyte (CD8+), leukocyte (CD45+), and endothelial (CD31+) sEVs were detected.↑ levels of P-selectin on sEVs from APS pts. vs. HBDs.↑levels of CD133/1 on sEVs from APS pts. vs. aPL− pts. with thrombosis. Here, PECAM1 is linked to autoimmune polyendocrinopathy.