Abstract
Studies on sera from 65 children and 85 adults who had received repeated doses of [gamma]-globulin by blood transfusions revealed that 60% of the children and 30% of the adults had some form of antibody against y-globulin. In children, the predominant anti-[gamma]-globulin specificity was for one of the genetic (Gm) factors, although non-Gm specific, rheumatoid factor-like activity was also demonstrated. The thesis that these Gm-specific antibodies arose by immunization was transfused, genetically foreign [gamma]-globulin is supported by the occurrence of anti-Gm specificity only against a Gm factor absent in the patient''s [gamma]-globulin phenotype, the high incidence of this activity compared to a non-transfused, control population, the development under observation of anti-Gm activity in one patient at the age of 15 years, and the frequent absence of the immunizing Gm factor in the maternal [gamma]-globulin. In adults, hem agglutinating antibody directed against a number of human incomplete anti-D''s was found, none specific for Gm factors. These studies document the antigenicity of isologous [gamma]-globulin for man and show that Gm-specific antibodies and rheumatoid factor-like activity may arise by immunization with isologous [gamma]-globulin. They are compatible with the concept that anti-[gamma]-globulins occurring in patients with rheumatoid arthritis are antibody in nature.