Fig. 3.

Agonist activity of peptides at human C5a₁ and C3a receptors expressed in rat basophilic leukemia cells (RBL-2H3). Peptides were dissolved in DMSO and incubated at 50 μM with RBL-2H3 cells transfected with the appropriate receptor for 15 min. Degranulation was measured as the secretion of β-hexosaminidase. Results are expressed relative to maximal stimulation with 200 nM C5a (C5a₁) or 100 nM hexapeptide agonist FLPLAR (C3a) after subtraction of background. Statistical significance of the difference from zero was assessed using a one-sample t test (^⁎P<0.05; ^⁎⁎P<0.001). Bars are shaded according to peptide length (see Supplementary Table 2).