ENRICHMENT AND CHARACTERIZATION OF DENDRITIC CELLS FROM HUMAN BRONCHOALVEOLAR LAVAGES

In the present study about 0.3% to 1.6% of human bronchoalveolar lavag e (BAL) cells were identified as typical dendritic cells (DC), having an irregular outline, lobulated nucleus, and clear distinguishable aci d phosphatase activity or EBM11 (anti-CD68) reactivity in a spot near the nucleus. After DC enrichment, using transient adherence to plastic , FcR-panning, and a density metrizamide gradient, a population contai ning 7-8% typical DC was obtained. This DC-enriched low density fracti on, containing the highest percentages of DC, very strongly induced T cell proliferation in an allogeneic mixed leucocyte reaction (MLR), wh ich was significantly higher than that induced by other partly (un)fra ctionated BAL cells. These data indicate that DC seem to be the major accessory cells in the BAL fluid, and therefore may be important in th e regulation of T cell immune responses in the lung.