Figure 8.

Chemokine secretion of isolated LECs and BECs. (A and B) LECs, but not BECs, secrete SLC/CCL21, but both EC types produce MIP-3α/CCL20 upon activation. EC subsets grown to confluence were exposed to EGF- and hydrocortisone-deficient medium (non-stim.) or to the same medium supplemented with TNFα or IL-1β. 24 h supernatants were analyzed by CCL21- (A) and CCL20-specific ELISAs (B). The concentrations of chemokines produced by BECs (hatched bars) and LECs (black bars) are shown (mean values (±SD) obtained in two independent experiments). (C) LECs secrete CCL21 but not CCL20 basolaterally. LECs grown to confluence on 0.4-μm poresize Transwell^TM filters, were nonstimulated (non-stim.) or stimulated with TNFα- or IL-1β for 24 h. CCL21 (black bars) and CCL20 (hatched bars) secreted into the upper (apical) and the lower (basolateral) chamber of the Transwells™ were measured. The percentage of chemokine recovered from the lower chamber relative to the total amount of secreted chemokine (i.e., secreted into the upper and lower chamber) is shown. Mean values (±SD) obtained from triplicate cultures; n.d.; not done. (D) LEC monolayers form a tight barrier for exogenous CCL19 used as a tracer. To control for leakage of chemokines through the LEC monolayer, MIP-3β/CCL19 was added to the upper chamber. Data are given as the percentage of the amount of chemokine recovered from the lower chamber relative to the amount of chemokine retrieved from the upper and lower chamber. Approximately 80% of initially added CCL19 was recovered after 24 h. Mean values (±SD) obtained from triplicate cultures.