SSL5 inhibits leukocyte activation by chemokines and anaphylatoxins. (A,B) Neutrophils were incubated with (□) or without (■) 10 μg/mL SSL5 for 30 seconds and stimulated with (A) 1 nM fMLP, 10 nM MMK-1, 0.1 nM PAF, 0.1 nM LTB₄, 3 nM C3a, 0.1 nM C5a, or 0.5 nM IL-8 and with (B) 30 nM ionomycin or 1 μM ATP. Cell activation was measured by calcium mobilization (C-K). Neutrophils (C-F) or monocytes (G-K) were preincubated with 0 (■), 1 (▴), 3 (▾), or 10 (♦) μg/mL SSL5 for 30 seconds. Calcium mobilization was measured on stimulation with C3a (C), C5a (D), CXCL8 (E), CXCL1 (F), CXCL12 (G), CCL2 (H), CCL3 (I), CCL5 (J), or CX₃CL1 (K). Results represent mean plus or minus SEM of 3 independent experiments and are expressed relative to buffer-treated cells.