CELLULAR-HYPERSENSITIVITY TO TUBERCULIN IN BCG-REVACCINATED PERSONS STUDIED BY SKIN REACTIVITY, LEUKOCYTE MIGRATION-INHIBITION AND LYMPHOCYTE-PROLIFERATION

Abstract

Some persons seem to lose long-standing peripheral hypersensitivity to tuberculin earlier than others. This was seen in a group of 5 healthy student nurses who were BCG-vaccinated as children and were found, in routine skin testing, to be negative to 100 TU [tuberculin units] of tuberculin purified protein derivative (PPD). They were revaccinated, which resulted in conversion to 10 TU skin test positivity. In agreement with this, their buffy coat cells achieved reactivity to 100 .mu.g/ml of PPD in a leukocyte migration inhibitory factor (LIF) assay. The LIF response, maximal at 4 wk, faded earlier than skin reactivity. Peripheral blood lymphocyte proliferation was studied with several PPD concentrations, 10 .mu.g/ml always inducing the maximum 3H-thymidine uptake. This was still high at 6 mo. after vaccination, when skin reactions tended to be smaller than earlier. The reason why various parameters of cellular hypersensitivity followed different courses is not known, but it may involve different subpopulations of lymphocytes, activity of suppressor cells or influence by serum factors such as mycobacterial antigen-antibody complexes.