Abstract 5938: Detection of Cardiac Antibodies in Acute Rheumatic Fever and Rheumatic Heart Disease by Two-Dimensional Western Blot Analysis
Acute rheumatic fever (ARF) is an autoreactive disease secondary to a group A streptococcal infection involving the heart, joints, skin and brain. During an infection activated antigen presenting cells present the bacterial antigen to helper T cells, which subsequently activate B cells and induce the production of antibodies against the cell wall of streptococcus. These antibodies also react against the myocardium, producing the symptoms of rheumatic heart disease. The cell wall of group A streptococcus pyogenes is composed of branched polymers containing “M proteins” which are highly antigenic and may cross-react with cardiac myosin. Sera from 9 patients with acute rheumatic fever, 17 patients with chronic/rheumatic heart disease (CHD/RHD) and 17 controls from individuals without heart disease were probed in one-and two-dimensional Western blots for reactivity against heart tissue antigens, respectively. Antibodies against fragments of the myosin heavy chain were demonstrated in 77% of sera of patients with ARF, in 35% of sera of patients with CHD/RHD but not in control sera. Antibodies directed against proteins with a molecular weight of 50kd, 45kd, 37 kd and to a much lesser extend of 40kd were directed against a lysate of cardiac tissue (Fig.1⇓). Antibodies against 55 kd, 50kd, 45kd proteins from a lysate of streptococcus M-protein were not found in controls but in 44 – 77% of patients with ARF and in about 12 – 25 % of cases in CHD/RHD (Fig 2⇓). Sequence analysis of the above characterized proteins will possibly identify additional myocardial antigens involved in the secondary immunopathogenesis of ARF and CHD/RHD.