Direct migration inhibition test with leukocytes as indicator of mycobacterial antigens in the human body.

In 32 patients with newly detected pulmonary tuberculosis positive on smear and culture, included in a controlled clinical trial, a significant correlation between diminishing inhibition of leukocyte migration (induced by PPD) and reduction of mycobacterial population in the sputum during the course of chemotherapy has been demonstrated. The changes of mycobacterial population in the host have been assessed in two ways: an indirect assessment was made from the time taken to achieve sputum smear and culture negativity; a direct assessment was based on repeated quantitative determinations of tubercle bacilli in the sputum. The direct migration inhibition test with peripheral buff-coated leukocytes, is an easy and reliable correlate of delayed hypersensitivity to mycobacterial antigens in the human body. It is suggested that its use in individual patients could indicate changes in mycobacterial population, particularly after microbiological negativity has been obtained, and thus could be helpful in estimating the optimum duration of chemotherapy.