Abstract 2965: A Novel Autoantibody Against Ca2+ Channel in Patients with Idiopathic Dilated Cardiomyopathy
BACKGROUND: The disorder of Ca2+ channel deduced by autoimmunity played an important role in the pathogenesis of idiopathic dilated cardiomyopathy (IDC). The autoantibodies against ADP/ATP carrier in patients with IDC had cross reaction with the Ca2+ channel. We assessed the hypothesis that there were independent serum autoantibodies against the cardiac L-type Ca2+ channel (Cav1.2) in patients with IDC.
METHODS AND RESULTS: The synthesized peptide corresponding to a sequence of α1 subunit, human Cav1.2 was used as an antigen to screen sera from patients with IDC (n = 60) and healthy blood donors(n = 60) in ELISA . Meanwhile, the autoantibodies against ADP/ATP carrier were detected. The sera from 29 patients with IDC (29/60,48.33%) and 4 controls (4/60,6.67%, P < 0.01) recognized the antigen of human Cav1.2 in ELISA. There were no relationships between the autoantibodies against ADP/ATP carrier and the autoantibodies against Cav1.2(P > 0.05). Affinity-purified autoantibodies against Cav1.2 from positive sera of patients with IDC were detected by immunoblotting assay and immunofluorescence technique. Rat anti- Cav1.2 polyclonal antibodies were prepared and used as positive control. Affinity-purified autoantibodies from positive sera of patients with IDC recognized a major band of about 240kD (α1 subunit, Cav1.2) on the electrotransferred protein of rat ventricular cell membrane. This band was monospecific since its staining was blocked after preincubation with the Cav1.2 peptide and it coincided well with the band revealed by rat anti-Cav1.2 polyclonal antibodies. In immunofluorescence, the affinity-purified autoantibodies specially binded to the membranes of rat ventricular myocytes while the negative sera showed no binding.
CONCLUSIONS: The findings confirmed that we found a novel autoantibody against Ca2+ channel (Cav1.2) in patients with IDC, the function of the autoantibody will be researched further.