Anti-PPD Immunoglobulin G in Tuberculosis Patients

Sera from patients with active tuberculosis, treated tuberculosis, non-tuberculous pul­ monary diseases and from healthy subjects before and 3 months after BCGvaccination were assay­ ed for immunoglobulin G antibody against purified protein derivative by an enzyme-linked immu­ nosorbent assay using polystyrene microtitre plate. Marked increase in immunoglobulin G anti­ body activity in patients with active tuberculosis was seen (P = 0.006) but there were some degrees of overlap between the values for tuberculosis group and those for non-tuberculous pulmonary diseases and healthy subjects. Level of immunoglobulin G antibody activity increased with age in healthy Papua New Guineans (P = 0.044). Activity of immunoglobulin G antibody before and three months after BCG vaccination in seven nurse students was not significantly different (P = 0.133). This assay has potential as a rapid diagnostic tool for detection of active tuberculosis. (key words: PPD, immunoglobulin G, Tuberculosis, BCGvaccination) From the Royal Newcastle Hospital; University ofNewcastle, Australia. "Present address: Clinical Epidemiology Unit, Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700 Thailand