Association of altered dynamics of monocyte surface expression of human leukocyte antigen DR with immunosuppression in tuberculosis

Monocyte (MN) surface human leukocyte antigen DR was examined in 10 patients with pulmonary tuberculosis (TB) and 12 healthy individuals using OK11, a mouse monoclonal antibody to human DR, in a ⁵¹Cr-release cytotoxicity assay. Of freshly isolated MNs from TB patients, 39.1% ± 4.4% (mean ± SEM) were DR⁺, compared with 57.2% ± 5.7% in healthy subjects (P < 0.02). After 24 hr in culture, a sharp rise was observed in the TB group, to 78.1% ± 11.6% (P < 0.005), compared with 64.9% ± 5.1% in the control group. The TB patient group could be subdivided on the basis of tuberculin purified protein derivative-induced [³H]thymidine incorporation in peripheral blood mononuclear cells (PBMCs). A significantly smaller fraction of MNs from tuberculin nonresponder TB patients was DR⁺ (34.6% ± 6.0%) compared with healthy controls (59.4% ± 8.6%; P < 0.05). In the nonresponder group, a greater fraction of PBMCs was identifiable as MNs by cytochemical techniques (51.2% ± 3.6% vs 38.0% ± 5.0% in the responder group; P < 0.02). Cell mixing experiments demonstrated increased suppressor activity of DR^- MNs.