Comparison of a leucocyte adherence test with the leucocyte migration inhibition test and skin reactivity to PPD.

Using PPD as antigen, a leucocyte adherence test was compared with the leucocyte migration inhibition test and with the results of skin testing in healthy subjects. In the presence of antigen, leucocyte adherence was significantly greater in skin test-positive subjects than in skin test-negative subjects who had not previously had BCG vaccination. When the test was performed in heterologous serum, skin test-negative subjects who had had previous BCG vaccination showed significantly greater leucocyte adherence in the presence of antigen than skin test-negative subjects who had not had BCG vaccination; this difference was not present in autologous serum and its abolition was attributed to a serum blocking effect. The leucocyte adherence test correlated with the results of the leucocyte migration inhibition test in heterologous serum, and also with the results of skin testing interpreted in the light of previous vaccination history. The finding of increased rather than decreased adherence in the presence of antigen, although previously reported, is unusual.