QUANTITATIVE STUDIES OF THE IMMUNOGLOBULIN SEQUENCE IN THE RESPONSE OF THE RABBIT TO A SOMATIC ANTIGEN

Abstract

Employing a sensitive and immunoglobulin-specific assay method based upon anti-globulin augmentation, quantitative and qualitative aspects of the primary and secondary response of the rabbit to Salmonella typhimurium O antigens have been evaluated. These studies examine the validity of the method of assay for detecting and measuring [gamma]G- and [gamma] M-antibodies produced in response to whole organisms or its lipopolysaccharide. The results show that during the primary response [gamma]G-antibodies, not detectable by usual techniques, are produced in a pattern similar to that reported in animals stimulated by other classes of antigens. Moreover, the yG response following reinjection is characteristic of a secondary-type response. In contrast, [gamma]M-antibody levels after both primary and secondary stimulation rose equally to levels between 1 and 4 mg/ml. Despite increased sensitivity of detection and quantitative estimates of the actua molar concentration of each immunoglobulin, the minimal interval between [gamma]M and [gamma]G appearance in serum was not less than 1.5 days. The variable degree of augmentation of agglutination by antiglobulin reagent found during the immune response severely limits the quantitative usefulness of the methods developed. However, the data suggest that qualitative changes in anti-O antibodies interpretable as changes in avidity occur regularly during the immune response.