Dilated cardiomyopathy defines serum autoantibodies against G-protein-coupled cardiovascular receptors.
In order further to identify the prevalence of anti-receptor autoantibodies in the sera of patients with dilated cardiomyopathy (DCM), we attempted to detect autoantibodies against a series of G-protein-coupled cardiovascular receptors in a well-defined population of DCM patients from Japan. Peptides corresponding to the sequences of the second extracellular loops of the human beta 1 and beta 2 adrenoceptors, alpha 1 adrenoceptors, M2 muscarinic acetylcholine receptors and angiotensin II-1 (AT1) receptors were used as antigens in an enzyme immunoassay to screen the sera from patients with DCM (n = 28). Nine sera from patients with DCM (32%) and 2 sera from healthy subjects (9%) recognized the beta 1 adrenoceptor peptide. Ten sera from patients (36%) and 3 sera from healthy subjects (13%) recognized the M2 receptor peptide. Thirty-six per cent of the patients with autoantibody against the beta 1 adrenoceptor peptide. Ten sera from patients (36%) and 3 sera from healthy subjects (13%) recognized the M2 receptor peptide. Thirty-six per cent of the patients with autoantibody against the beta 1 adrenoceptor had autoantibody against the M2 receptor. However, no significantly high frequencies of autoantibodies against the beta 2 adrenoceptor, alpha 1 adrenoceptor and AT1 receptor were found in DCM patients. Our results demonstrate that a subgroup of patients with DCM have a specific spectrum of autoantibodies which are specifically directed against the second extracellular loops of the beta 1 adrenoceptors and M2 muscarinic receptors rather than other cardiovascular receptors.
Matsui
S
S
Department of Cardiology, Kanazawa Medical University, Japan.
Fu
M L
ML
Shimizu
M
M
Fukuoka
T
T
Teraoka
K
K
Takekoshi
N
N
Murakami
E
E
Hjalmarson
A
A
D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D001323:Autoantibodies / Q000276:immunology*; D002311:Cardiomyopathy, Dilated / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019204:GTP-Binding Proteins / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011941:Receptors, Adrenergic / Q000737:chemistry / Q000276:immunology*; D011945:Receptors, Angiotensin / Q000737:chemistry / Q000276:immunology*; D011976:Receptors, Muscarinic / Q000737:chemistry / Q000276:immunology*
D001323:Autoantibodies; D010455:Peptides; D011941:Receptors, Adrenergic; D011945:Receptors, Angiotensin; D011976:Receptors, Muscarinic; D019204:GTP-Binding Proteins