Abstracts

Recurrent epileptiform seizures affect approximately 3% of the United States population. Despite the high frequency of seizure disorders the biochemical etiology remains largely unknown. Indeed, only approximately 10% of the epilepsies have a known cause. It is well established that iron via generation of reactive oxygen species can cause tissue damage. Also iron, has been suggested to be involved in pathogenesis of epilepsy. Hemoglobin is the richest source of iron in the body, and may have a role in tissue injury. Haptoglobin (Hp) is an acute phase reactant that removes free hemoglobin from circulation; possibly to prevent hemoglobin mediated renal damage. Hp has three phenotypes (Hp 1-1, Hp 2-2 and Hp 2-1) in which type
1-1 is biologically the most active. We have previously shown that patients with familial idiopathic epilepsy suffer from hypo or anhaptoglobinemia. The purpose of this study was to investigate the role of Hp in epilepsy by correlating plasma Hp levels and phenotypes with severity and frequency of seizure events. Leftover specimens from patients visited Harborview Medical Center (HMC) for controlling their seizures were randomly selected. Controls were patients without epilepsy, liver or hemolytic disorders who visited HMC for check up.
Determination of haptoglobin phenotypes:
Hp phenotyping is performed by means of gel electrophoresis followed by peroxidase staining (Smithies, 1955). Serum was stored at [ndash]70until used. Haptoglobin phenotyping was determined from 10 ml of plasma by polyacrylamide gel electrophoresis. The three different phenotypes are distinguishable by a characteristic pattern of bands representing haptoglobin-hemoglobin complexes. The Haptoglobin analysis was performed without any knowledge of the patients[rsquo] status.
[italic]Serum Haptoglobin measurement:[/italic]
Hp concentration was determined by fixed-time immunonephelometery on a Dade Behring nephelometer using Dade Behring rabbit anti-human haptoglobin commercial antibodies (Sigma chemical Company, St. Louis, MO).
Our preliminary results show strong correlation between Hp phenotype and severity of seizure. That is, 71% of epileptic patients with frequent seizure had Hp 2-2, and one patient had no Hp. Only 16% of patients had Hp type 2-1 and 12% had type Hp 1-1. In contrast, Hp phenotypes were evenly distributed in our control population; Hp 1-1 (30%), Hp 2-1 (31%) and Hp 2-2 (39%). Plasma Hp levels range widely among patients (2-2: 115 [plusmn] 56; 2-1:152 [plusmn] 76 and 1-1:151 [plusmn] 79 mg/dl; mean [plusmn] SD) and among controls (2-2: 146.57 [plusmn] 87.90; 2-1: 163.36 [plusmn] 51.50; and 1-1 138 [plusmn] 5.66 mg/dl; mean [plusmn] SD). There was a direct correlation between C-Reactive Protein (CRP) and phenotype 2-2. There was a reverse correlation between transferrin and phenotype 2-2.
In conclusion, Hp 2-2 is associated with more frequent and severe seizure and Hp 1-1 is associated with mild and less frequent seizure. Therefore, Hp may have a role in pathophysiology of seizure.