DELAYED-HYPERSENSITIVITY AND HLA IN SMEAR-POSITIVE PULMONARY TUBERCULOSIS

Tuberculin responses were quantified by induration of the skin, veloci ty of blood flow in dermal microcirculation and composition of the cel lular infiltrate in 125 patients with tuberculosis and 39 healthy cont rols. The diameters of the tuberculin responses were greater in HLA-DR 15-positive patients than in DR15-negative patients. The density of in filtrating CD4+-positive cells showed a positive correlation with indu ration in DR15-negative subjects (r = 0.54), A fraction of DR15-positi ve patients gave large tuberculin responses (greater than or equal to 15 mm) but with few CD4+ cells in the test site (<500/mm(2)); these pa tients had a greater percentage of cells in the diffuse dermal infiltr ate than in the perivascular region, greater blood flow velocities in the tuberculin response but more frequently with central relative slow ing of blood flow and had higher total IgG and specific antimycobacter ial antibody levels compared to other DR15-positive patients. If the i nflammatory infiltrate in the lungs parallels that in the tuberculin s kin test, the lack of immunocompetent cells and tissue hypoxia could p ermit pulmonary cavitation and explain the association of HLA-DR15 wit h smear-positive pulmonary tuberculosis.