Fig. 3.

Unlike PMNs, SRBCs require sialidase pretreatment to accept the ST-mediated transfer of sialyl residues. CMP-5-FITC-NEU (25 μM) was added to PMNs and SRBCs, which were treated (closed bars) or not treated (open bars) with sialidase (25 mU/ml for 1 h at 37ºC). Following the addition of an exogenous source of ST (α2,6-ST, 0.5 nU/ml), the cells were incubated at 37ºC for 2 h and analyzed by flow cytometry. Intact PMNs were used as a source of ST with intact PMNs as acceptor cells, and a similar number of SRBCs were added to SRBCs to assess whether these cells provided endogenous ST activity. The data represent the mean ± sem of four wells per variable. This experiment is representative of an experiment repeated three times. The data were analyzed by one-way ANOVA with comparison among groups analyzed by Tukey’s multiple comparison test. *, P < 0.001; **, P < 0.01; ***, P < 0.05; #, P> 0.05.