Rheumatoid Factors in Subacute Bacterial Endocarditis—Bacterium, Duration of Disease or Genetic Predisposition?

Abstract

Patients (43) with subacute bacterial endocarditis (SBE) were studied to define what clinical features were important in the development of anti-gamma-globulin factors during the course of infection. Forty-seven % showed positive latex fixation tests and more than 1/2 some type of anti-gamma-globulin factor during the course of the illness. A high degree of correlation between quantitative serum elevations of gamma G and positive tests for rheumatoid factors was noted. The quantitative elevations of gammaG could not be directly related to infecting bacteria since absorption of sera with the latter produced no more than a 15% decrease in gamma G immunoglobulin. Most patients who developed positive latex fixation tests had a duration of active SBE greater than 6 wk. An attempt was made to relate the development of a positive latex fixation test to genetic predisposition for the production of various autoantibodies. Relatives from latex positive and negative patients with SBE showed no gross differences in immunoglobulin levels or background autoantibodies to nuclear constituents, thyro-globulin or gamma-globulin. The most important factors in determining whether patients with SBE develop anti-gamma-globulin factors appeared to be duration of infection and quantitative serum elevations of gamma G.