[The Cytologic Ultrastructure and Cytochemical Features of Human Dendritic Cells from Peripheral Blood]

Objective: To observe the cytomorphological, cellular ultrastructure and cytochemical features of the dendritic cell (DC) enriched populations in vitro.

Methods: Fresh peripheral blood from healthy volunteers was collected and mononuclear cells (PBMC) were isolated on lymphocyte separating solution. The PBMC were cultured in mediums containing rhGM-CSF, rhIL-4 and rhTNF-alpha 9-12 days to generate DC-enriched populations, the morphological features and numbers of DC were identified and counted respectively by light microscope (LM) and confirmed by immunofluorescence assay (IFA), the ultrastructure characteristics of the DC populations were observed by transmission electron microscope, and the cytochemical features of them were also examined.

Results: The percentage of DCs was 70%-80% in the DC-enriched populations as confirmed by IFA using mABXII. Transmission electron microscopy revealed that the DC populations contained two subsets of DC, one was considered as precursor cell derived DC(PC-DC), the cell surface of which had many irregular dendrites with a irregular nucleus, small nucleoli, numerous mitochondria, but scanty lysosomes, ribosome, rough endoplasmic reticulum and free polysomes. Cytochemical staining showed the DCs were both peroxidase (POX) and non-specific esterase (NSE) negative. The other was indentified as monocyte-derived DC(MO-DC), the features of which included: irregular shape, many ruffles and some rough lames on cell surfaces, nephritic or horseshoe nuclei with a thick rim of heterochromatin, numerous mitochondria, much more lysosomes, ribosomes, rough endoplasmic reticulum and Golgiosome. The cytochemical reactions indicated that most of them had POX-positive granules, and were NSE slightly positive.

Conclusion: Cytokines in vitro induced DCs from human peripheral blood are heterogeneous.