OBJECTIVETo study the roles of platelet (PLT) and its regulating factors, megakaryocyte, thrombopoietin (TPO) and transforming growth factor beta1 (TGF-beta1), in immune vasculitis in young rabbits.

METHODSAn experimental model of Kawasaki disease (KD) of weanling rabbits was reproduced by bovine serum. PLT count, total number and differentiating count of megakaryocyte, and serum TPO and TGF-beta1 levels were measured 0, 4, 8, 12, 16, 20, 24 and 28 days after KD induction. Pathological analysis of coronary artery, liver, spleen, kidney and brain was performed 17 and 28 days after KD induction.

RESULTSIn the KD group, PLT count, the total number of megakaryocyte, and the middle board megakaryocyte percentage increased 12, 16, 20, 24 and 28 days; serum TPO level increased 8, 12, 16, 20, 24 and 28 days; serum TGF-beta1 level increased 16, 20, 24 and 28 days after KD induction compared with those in the normal control group (p<0.05). The pathological examinations of coronary artery, liver, spleen, kidney and brain showed severe inflammatory injuries of tiny arteries and small/medium-sized arteries 17 and 28 days after KD induction, respectively in the KD group. The aortas were showed as mild inflammatory injuries.

CONCLUSIONSPLT, megakaryocyte, TPO and TGF-beta1 participate in the pathogenesis of KD, and they may play an important role in the injuries of immune vasculitis. This suggests that they may serve as markers for the assessment of severity in KD.