Detection of immunoglobulin G antibody to purified protein derivative in patients with tuberculosis by radioimmunoassay and enzyme-linked immunosorbent assay

Sera from patients with active tuberculosis and sera from appropriate control individuals were assayed for immunoglobulin G antibody activity to purified protein derivative by a polystyrene tube radioimmunoassay and an enzyme-linked immunosorbent assay. Both assays showed a marked increase in immunoglobulin G antibody activity in patients with active tuberculosis. There was no overlap between the values for the patient group and the values for the purified protein derivative skin test-positive control individuals. The replication of these assays was excellent, and both could provide quantitative measurements of immunoglobulin G antibody activity to purified protein derivative antigen within 24 h. These techniques have potential as rapid diagnostic aids in evaluating patients with suspected active tuberculosis.