Expression of interleukin-10 in isolated CD8(+) T cells and monocytes fromgrowth factor-mobilized peripheral blood stem cell products: A mechanism of immune dysfunction

Previous reports showed the abnormal activation of immune cells in growth f actor-mobilized peripheral blood stem cell (PBSC) products, which might be responsible for depressed T cell responsiveness to mitogens compared with n ormal peripheral blood mononuclear cells (PBMC), In the present study, the mRNA expression levels of interleukin (IL)-2, IL-4, IL-10, and interferon-g amma (IFN-gamma) were significantly higher in CD4(+) and CD8(+) T cells fro m mobilized PBSC products compared with CD4+ and CD8+ cells from normal per ipheral blood (PB), The mRNA expression levels of IL-4 and IL-10 were signi ficantly higher in CD8(+) compared with CD4(+) cells from PBSC products, Ho wever, the expression of 11,-2 and IFN-gamma mRNA transcripts was similar i n the CD4(+) and CD8(+) T cells from PBSC products, The levels of IL-10, IL -8, and tumor necrosis factor (TNF)-alpha mRNA were also significantly high er in monocytes isolated from PBSC products compared with monocytes isolate d from normal PB, Expression of IL-10-specific mRNA in monocytes also was s ignificantly higher than the levels observed in CD8(+) cells from PBSC prod ucts, We suggest that both CD4(+) and CD8(+) cells in the PBSC products are highly activated, However, their response to phytohemagglutinin (PHA) mito genesis is depressed in part because of IL-10 expression by CD8(+) cells an d monocytes in addition to the higher levels of monocyte-dependent T cell i nhibitory activity, These data demonstrate that aberrant IL-10 expression i n the CD8(+) T cells and monocytes present in PBSC products may represent a possible mechanism of immune dysfunction in patients after high-dose chemo therapy (HDT) and peripheral blood stem cell transplantation (PBSCT).