Uneven distribution of antitreponema antibody acitivity in differing immunoglobulin G fractions from patients with early syphilis.

Three fractions, containing immunoglobulin G's (IgG's) of differing relative electrophoretic mobility, were isolated from sera of 33 male patients with untreated early syphilis. Serological testing, employing four different serodiagnostic procedures for these fractions at equal amounts of IgG, revealed a very constant reaction pattern for all patients. In the earliest stages of the disease, the most basic fraction was the first to show antibody activity. In progressive stages, antibody activity subsequently was also found in the two less basic fractions. However, in all stages of disease studied, the basic part of the IgG made the largest contribution of the total antibody activity within the IgG class, indicating an uneven distribution of antitreponema antibody activity over heterogeneous IgG. Several possible explanations of the observations are discussed.