Increased phagocytotic activity but decreased ability for antigen processing and antigen presentation in macrophages isolated from anergizing MLR cultures.

(A) CD14⁺ cells isolated from the indicated culture conditions were incubated with FITC-dextran for various time intervals, and endocytotic capacity was determined by flow cytometry. Results are representative of 3 experiments. (B) Following the indicated conditions and time intervals of MLR cultures, supernatants were isolated and examined for production of NO by colorimetric enzymatic assay. Results are representative of 2 experiments. (C) CFSE-labeled responder PBMCs were cultured with irradiated unlabeled (CFSE-negative) allogeneic stimulators. At various time intervals of culture, labeled CFSE-positive responder and unlabeled CFSE-negative stimulator populations were examined by flow cytometry. Results are representative of 4 experiments. (D) PBMCs from rigorous PPD responder individuals were cultured in 1:1 ratio with irradiated allogeneic PBMCs as stimulators with either medium or anti–B7-1 plus anti–B7-2 mAbs. After 7 days of culture, CD14⁺ cells were isolated, loaded with PPD, and used to stimulate autologous purified T cells. As controls, freshly isolated CD14⁺ cells were loaded with PPD and used as stimulators of autologous T cells in the same experiment. Response was determined by ³H-thymidine incorporation for the last 18 hours of the 5-day culture period.