997-87 ELISA Tltres of Anti-α Myosin Antibodies in Idiopathic Dilated Cardiomyopathy Patients Reduce with Disease Progression

Abstract

Immunofluorescence detects anti-heart antibodies directed against a range of cardiac antigens in 30% of patients with idiopathic dilated cardiomyopathy (DCM), but is not antigen specific, Western blots showed that these antibodies recognise both α (organ specific, atrial) and β (cross reactive ventricular and skeletal) myosin but this technique is nonquantitative and unsuitable for screening purposes. To assess the frequency and titre of the anti-a myosin antibodies, we developed a biotin-streptavidin ELISA for detection of IgG to purified human atrial myosin. A pilot study of 40 DCM patients and 40 IHD controls revealed 94% concordance between ELISA and Western Blot. Studies were performed on sera (dilution 1/320) from 123 consecutive patients with OCM (WHO criteria) presenting to our hospital (age 42 ± 14). These were compared with sera from 52 normals (45 ± 16) and 58 patients with ischaemic heart disease (IHD) (65 ± 12), (40% had poor LV function, 65% had previous MI). Raised antibody levels to atrial myosin were found in 24 (20%) of DCM patients, 1 (2%1 normal control and 3 (5%) of the IHD patients (DCM v. IHD p < 0.05, IHD v. normal p = 0.4). Mean antibody level ± SEM in DCM patients were greater than IHD patients (0.27 ± 0.02 v. 0.20 ± 0.01; P = 0.001) but IHD did not differ from normals (0.20 ± 0.01 v. 0.18 ± 0.01; P > 0.1 ). Repeat evaluation on 57 DCM patients after 20 ± 20 months showed significant reduction in antibody level from 0.3 ± 0.02 to 0.23 ± 0.01 (p = 0.04). In conclusion we confirm the presence of disease specific anti-α myosin antibodies in DCM patients and show a reduction in antibody level over time as in other autoimmune diseases.