Auto-Immunity Against IgG: Study of a Girl who had Undue Susceptibility to Infection and an IgM-IgG Euglobulin Complex in her Serum

摘要

Extract: A girl who had had severe recurrent infections from the seventh year of life and who died from the sequelae of extensive bronchiectasis at 18 years of age was studied. The serum of the patient contained a large amount of protein that could be isolated because of the character of the euglobulin. Ultracentrifugation showed that the serum consisted of two fractions with sedimentation constants of 17.4 S and 26 S, respectively. When this euglobulin had been removed, IgM and IgG were no longer identifiable in the serum, although increased concentrations of IgA were present. The macro-globulin was found to contain IgM and IgG determinants that showed antirabbit and antihuman IgG antibody characteristics. Specificity against a particular type of IgG was absent. The two components could not be dissociated in an acid medium or by 6 M urea. Separation by 0.1 M mercaptoethanol, however, yielded two fractions, an 11 S fraction containing both IgM and IgG determinants and a 7 S fraction containing IgM determinants only. It was concluded that the presence of IgM and IgG determinants in the euglobulin was caused by antibody activity of the IgM directed against the IgG of the patient.Speculation: Excessive susceptibility to bacterial infection is usually due to deficient antibody production. The present study, however, showed that symptoms of the antibody deficiency syndrome may also occur when antibody production is at least partly unimpaired. The macroglobulin present in serum displays antibody activity against IgG. It is speculated that auto-immunization against the IgG of the patient had occurred and that the macroglobulin would bind any IgG antibodies produced during infection. A clinical picture of the antibody deficiency syndrome thus results. The question of whether this auto-immunization is an uncommon feature should be explored. It is probable that production of auto-antibodies could have been a factor in various cases of dysimmunoglobulinemia reported previously.