Fig. 6.

CMP inhibits endogenous ST activity. (A). PMNs (8×10⁶) were added to 10 μM CMP-5-FITC-NEU in the absence (solid peak) or presence (open peak) of 0.3 mM CMP and analyzed by flow cytometry. CMP treatment reduced the MFI from 364 to 222. (B) To determine if intact, untreated PMNs exhibit some basal level of sialidase activity necessary to expose sialyl acceptor sites for the ST activity, PMNs were analyzed in the absence (solid peak) or presence (open peak) of 2-DN (0.04 mM), an inhibitor of sialidase activity. A small but highly reproducible reduction in ST activity was noted (reduction in MFI from 364 to 317). The data show a single experiment that was repeated independently three times.