Skip to main content
. Author manuscript; available in PMC: 2020 Feb 1.
Published in final edited form as: J Allergy Clin Immunol. 2018 May 17;143(2):669–680.e12. doi: 10.1016/j.jaci.2018.05.003

Figure 5. R321 does not inhibit CCL11-induced CCR3 internalization and does not induce resistance (tolerance) to inhibition of CCL11-induced chemotaxis.

Figure 5

(A) R321 does not inhibit CCL11-mediated internalization of CCR3. When added concurrently with 12 nM CCL11, R321 (1μM) and R323 (1μM) did not interfere with CCL11-induced receptor internalization. Both SB328437 (1 μM) and UCB35625 (1 μM) significantly inhibited the chemokine’s ability to induce CCR3 internalization. (B) R321 alone decreases CCR3 surface expression. R321 dose-response reduction of surface CCR3 expression on AML14.3D10-CCR3 cells. Significant internalization levels were reached at 1μM R321. (C) R321 maintains prolonged inhibitory activity. AML14.3D10-CCR3 cells were treated for 24h, 48h or 72h with R321 or unbiased antagonists (all at 1 μM) ± CCL11 (12 nM). (D) R321 promotes CCR3 internalization in human blood eosinophils over a prolonged incubation period. Results shown as surface expression of CCR3 as percentage of vehicle expression. Of note, SB328437, when used at equimolar concentrations to R321 and UCB35625 (1μM), was a less effective inhibitor of CCL11/CCR3-mediated chemotaxis and failed to promote CCR3 cell surface accumulation. Results represent mean ± SEM from experiments (n=3) performed in triplicate. Compared to vehicle (B, D) or 24h data point (C): *p ≤ 0.05, **p ≤ 0.01, ***p<0.001, ****p ≤ 0.0001; Error bars = SEM.