Autoantibodies against cardiac G-protein-coupled receptors define different populations with cardiomyopathies but not with hypertension.

• It was previously shown that the second extracellular loop of cardiovascular G-protein-coupled receptors is an antigenic target for pharmacologically active autoantibodies in patients with idiopathic dilated cardiomyopathy. To extend these observations to cover patients with the same disease from different geographical origins or to patients with other cardiac diseases, peptides corresponding to the sequences of the second extracellular loops of the human M2 muscarinic receptors and beta adrenoceptors were used as antigens in an enzyme immunoassay. Sera from patients from Sweden and Japan with idiopathic dilated cardiomyopathy (DCM, n = 32), hypertrophic cardiomyopathy (HCM, n = 23), malignant essential hypertension (MEH, n = 11), malignant secondary hypertension (MSH, n = 10), and sera from healthy blood donors (HBD, n = 49) were tested. Sera from patients with DCM recognized the muscarinic receptor peptide in 38% of cases and the beta 1 adrenoceptor peptide in 31% of cases. In 50% of the positive patients, autoantibodies against both peptides coexisted as shown by competition experiments using both peptides as inhibitors. In HCM patients, there was a lower frequency of autoantibodies but with a higher but not significant predominance against the M2 peptide. No autoantibodies were detected in sera from patients with MEH or MSH. Autoantibodies against the M2 muscarinic receptors, affinity-purified from positive patients, displayed pharmacological activity as demonstrated by changes in the affinity and number of radioligand binding sites. In contrast, antibodies purified from positive HBD had no effect. These results confirm that autoantibodies displaying pharmacological activity against G-protein-coupled cardiovascular receptors are mainly restricted to patients with idiopathic dilated cardiomyopathy and that different autoantibody populations are responsible for the recognition of the different receptors.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Mikrobiologi inom det medicinska området (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Microbiology in the medical area (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Fysiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Physiology (hsv//eng)

Nyckelord

Adult

Aged

Amino Acid Sequence

Animals

Autoantibodies

physiology

Cardiomyopathy

Dilated

immunology

Cardiomyopathy

Hypertrophic

complications

immunology

Cross Reactions

immunology

Enzyme-Linked Immunosorbent Assay

Female

GTP-Binding Proteins

immunology

Humans

Hypertension

complications

immunology

Immunoglobulin Isotypes

physiology

Male

Middle Aged

Molecular Sequence Data

Peptide Fragments

immunology

Rats

Receptors

Adrenergic

beta

immunology

Receptors

Muscarinic

immunology

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)