Defective yeast opsonisation of serum in tuberculosis.

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.