A comparison of the direct and indirect leukocyte migration tests in man.

In the Direct Leukocyte Migration Test, as few as 10% mononuclear cells are sufficient to produce antigen-specific inhibition of polymorphonuclear leukocyte migration in the presence of 100 mug of excipient-free PPD per ml. A clear distinction between tuberculin-positive and tuberculin-negative donors can be made. The inhibition of migration is blocked by the presence of actinomycin D. In the Indirect Test, significant inhibition of migration of pure polymorphs is produced by supernatants from stimulated tuberculin-sensitive lymphocyte cultures. Inhibition is maximal at 6 h and is of a similar degree to that obtained in the direct test.