Humoral immune response in tuberculosis: initial characterization by immunoprecipitation of 125iodine labelled antigens and sodium dodecyl sulfate polyacrylamide gel electrophoresis.

125Iodine-labelled Mycobacterium tuberculosis antigens were immunoprecipitated with tuberculosis patients' sera and analysed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. A group of four polypeptide antigens of 55, 38, 28 and 18 kD were thus identified. The 38 and 28 kD polypeptides were the major antigens. Antibody response differed from one patient to another, both with respect to the number and quantity of antigens precipitated. Untreated patients and those undergoing treatment with antimycobacterial drugs also showed marked differences in their antibody response. Generally, immunoprecipitates from treated patients showed a larger number of antigen bands and the relative intensities of the bands was also greater. No correlation was observed between the immunoprecipitation profile and antibody titres determined by enzyme linked immunosorbent assay.