Surface phenotype analysis of CD16(+) monocytes from leukapheresis collections for peripheral blood progenitors

In peripheral blood progenitor cell (PBPC) collections from patients with s olid tumour or haematological malignancy, monocytes were separated into two subpopulations. The majority of monocytes expressed CD14 at a high density without CD16 antigen (the CD14(+) CD16(-) monocytes). The remaining monocy tes co-expressed CD14 and CD16 (the CD14(+) CD16(+) monocytes). These CD14( +) CD16(+) monocytes amounted to 20.6 +/- 15.8%, while those in peripheral blood (PB) obtained from healthy volunteers were 7.3 +/- 3.1% (P < 0.05). W hen subdividing the CD14(+) CD16(+) monocytes into CD14(bright) CD16(dim) a nd CD14(dim) CD16(bright) cells, both populations were found to be increase d in PBPC collections. Since typical CD14(+) CD16(+) monocytes are the CD14 (dim) CD16(bright) population, we compared the additional surface antigens on CD14(dim) CD16(bright) monocytes with those of CD14(+) CD16(+) monocytes . In PBPC collections, the CD14(dim) CD16(bright) monocytes exhibited lower levels of CD11b, CD15, CD33 and CD38 expression and higher levels of CD4, CD11a, CD11c and MHC class II, and also revealed a higher percentage of CD4 (+) cells and a lower percentage of CD15(+) cells and CD38(+) cells, compar ed with the CD14(+)CD16(+) monocytes. When compared with the CD14(dim) CD16 (bright) monocytes in PB, those in PBPC collections exhibited higher expres sion of CD4 and lower expression of CD11b, and also showed higher percentag es of CD4(+) cells and CD38(+) cells and a lower percentage of CD11b(+) cel ls. These results suggest that PBPC collections may be rich in the CD14(+)C D16(+) monocytes in which the proportion of the immature population is incr eased. It is likely that these monocytes participate in the haematological and immune recovery after PBPC transplantation.