Apolipoprotein and anticardiolipin antibodies in patients with renal amyloidosis

Thromboembolic events are seen more frequently in patients with chronic renal failure (CRF) and amyloidosis. The anticardiolipin antibody (ACA) that is important for thromboembolic events has never been studied.

This study included 43 amyloidosis patients of different aetiologies; 28 with CRF as well as 20 patients who had CRF without amyloidosis. Thirty normal subjects were included as a control group. We determined the serum levels of ACA, apolipoprotein AI (ApoAl), ApoE and lipoprotein (a) (Lp(a)) in these groups.

Anticardiolipin antibody was found to be positive in 30.2% of patients with amyloidosis, this is in contrast to 3.3% in the control group (chi = 8.25, P < 0.005). We also showed that there was a statistically significant difference (chi = 5.03, P < 0.05) between the CRF patients with amyloidosis (31%) and the CRF patients without amyloidosis (5%). The average levels of serum ApoAI were shown to be significantly lower (P < 0.05) in CRF patients with amyloidosis in comparison with the amyloidosis patients who had normal renal functions (93.60 +/- 27.84 vs 119.8 +/- 36.26 mg/dL, P < 0.05). There was also significant a difference in ApoAI levels between CRF patients with and without amyloidosis (P < 0.001). The serum Lp (a) levels were significantly higher in CRF patients with amyloidosis when compared with the controls (41.2 +/- 22.39 vs 19.13 +/- 8.78 mg/dL, P < 0.001). The serum Lp (a) levels were also positively correlated with ACA (r = 0.211; P < 0.05).

In conclusion, ACA positivity is more common in all patients with amyloidosis as compared with CRF patients and normal controls. This study is the first to show the presence of high levels of ACA in patients with CRF, which is caused by secondary amyloidosis. Further studies are recommended to investigate the mechanism of this finding.