Cryosections of neutrophils from PB. (a) Localization of NAMLAA after incubation with the NAMLAA-specific MoAb AAA4. The gold label is shown in vesicles and granules (arrows). No background is shown on the nucleus (n). (b) Micrograph showing double labeling for NAMLAA (5 nm gold) and MPO, a marker for azurophilic granules (10 nm gold). Both labels were seen in some, but not in all, MPO-positive azurophilic granules. (c) Localization of lactoferrin (10 nm gold) and NAMLAA (5 nm gold) showed that the lactoferrin-positive specific granules (s) were not labeled with AAA4, whereas other granules/vesicles were labeled with AAA4 (arrows). Bars: (a), 200 nm; (b), 50 nm; (c), 100 nm.