Abstract

We have studied the opsonising ability of the sera of 92 patients with tuberculosis. Fourteen per cent of these patients showed defective opsonising ability compared with 4% in a clinic control group. This increased frequency in TB was accounted for by the greatly increased proportion with defects found in patients with intrathoracic TB (21%). We may have identified a section of the population with a specific genetically linked abnormality of a host defence mechanism which renders them more susceptible to intrathoracic TB. Further population studies are required.