Comparison of direct and indirect migration inhibition tests and skin hypersensitivity to tuberculin (PPD)

The direct macrophage and indirect leukocyte migration inhibition tests were used for the examination of patients with pulmonary tuberculosis and of their contacts. In the direct test at a concentration of 10 microgram PPD/ml medium, a statistically significant difference [p less than or equal to 0.001] was found between the mean values of MI [migration indices] in PPD-negative [MI = 0.98 +/- 0.10] and MI of PPD-positive to patients [MI = 0.60 +/- 0.10]. [PPD-negative = showing no reaction to ID administration of tuberculin, PPD-positive = showing a positive reaction to ID administration of tuberculin]. A statistically significant difference [p less than or equal to 0.05] was also found between the mean values of MI in tuberculin-positive to patients and healthy contacts [MI = 0.80 +/- 0.14]. By means of the indirect test we demonstrated a statistically significant inhibition of migration [p less than or equal to 0.001] in PPD highly positive contacts [MI = 0.76 +/- 0.10]. The results of the direct and indirect migration inhibition tests were found to agree in 66.6%.