Summary
Heparin cofactor II (HC II) is a thrombin inhibitor in human plasma which displays
great similarities with antithrombin III (AT III). Hereditary HC II deficiency was
recently reported to be associated with thrombophilia. Since thromboembolism constitutes
an important post-operative complication after renal transplantation, we measured
HC II and AT III in the plasma of 118 healthy renal allograft recipients (RAR) and
found stable low HC II and high AT III levels. Administration of azathioprine (AZA),
cyclosporine A (CSA) or both as immunosuppressive therapy did not affect HC II levels,
but CSA seems to have raised plasma AT III. The proportion of patients with HC II
deficiency was significantly higher in RAR than the proportion we previously found
(11) in healthy individuals (16.9% vs 1.5%). However, the proportions with low plasma
HC II were not different in healthy RAR and in ten RAR with thrombotic events, suggesting
that in transplanted patients, HC II deficiency is not in itself a risk factor for
the development of thrombosis.