Rheumatic Fever

Principles to understand

• after a strep throat, you make antibodies to Streptococcus

• when the Strep. is group A, there is an increased chance that some of the antibodies will cross-react with heart muscle and injure it

• there is also possibility of immune complex disease and endocarditis (infection of heart valve)

• penicillin rx of strep throat gets rid of the organisms faster so you don’t make these harmful antibodies and don’t have enough antigen to make immune complexes

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• sometimes people make antibodies to penicillin attached to red cells or platelets and destroy them

  • many people who say they are allergic to penicillin actually aren’t, but trust them anyway

Molecular mimicry

• streptococcal molecules and cardiac molecules are close enough that antibodies that recognize one recognize the other

• a similar situation is how antibodies against cytomegalovirus can cross-react with pancreatic β cells

Anti-basement-membrane antibodies in alveoli

• there is a nice smooth coating of antibody

• in kidney disease, we will get into the difference between smooth and bumpy-bumpy

Revised Jones criteria for diagnosis of acute rheumatic fever

• this is before we knew the exact mechanism

• major criteria

  • carditis: inflammation of the heart

  • polyarthritis

  • subcutaneous nodules in vessels in skin

  • Sydenham’s chorea, indicative of CNS damage (cerebral vasculitis)

• minor criteria

  • arthralgia: aching joints without apparent swelling

  • fever

  • increased acute-phase response as judged by a raised ESR or raised levels of CRP

  • prolonged PR interval, as detected by EKG

Category: Pathology Notes