Figure 2. TGF-β1 is able to inhibit LAP-induced monocyte recruitment.

(A) 10 pg/ml of rhLAP (dose with maximal response) was used as the chemoattractant for freshly isolated human peripheral blood monocytes in chemotaxis chambers and assessed as in previous experiments. Increasing doses of active rhTGF-β1 were pre-incubated with the chemoattractant prior to exposure to the monocyte suspensions (*, p<0.05 vs. LAP alone). (B) To compare this to the activity of LAP as an inhibitor of active rhTGF-β1 function in this system, we performed parallel experiments where the conditions were reversed. Active rhTGF-β1 was used at its maximal effective dose (100 pg/ml) based on prior experiments (data not shown). (*, p<0.05 vs. TGF-β1 alone) All bars represent the mean±SEM. (C) Assessment of LAP-mediated recruitment independent of TGF-β1 receptor activity in these experiments was assayed using SB 431542 hydrate, a selective inhibitor of TGF-β type 1 receptor kinases (TGF-β1-receptor inhibitor). Cell suspensions were preincubated for 20 minutes with 10 µM SB 431542 (optimal dose blocking TGF-β−induced signaling) or DMSO. 10 pg/ml of rhLAP (dose with maximal response) was used as the chemoattractant for freshly isolated human peripheral blood monocytes in chemotaxis chambers and assessed as in previous experiments. Increasing doses of active rhTGF-β1 were pre-incubated with the chemoattractant prior to exposure to the monocyte suspensions (*, p<0.05 vs. LAP alone) (*, p<0.05 vs. TGF-β1 alone). All bars represent the mean±SEM for n = 3 samples.