Effect of interleukin-7 on the in vitro development and maturation of monocyte derived human dendritic cells

We have compared the cell phenotype and functional properties of monocyte/m acrophage derived dendritic cells (DCs) obtained by culture of human adhere nt peripheral blood mononuclear cells (PBMCs) in medium containing granuloc yte macrophage colony stimulating factor (GM-CSF) either alone (GM-CSF-DCs) , or in combination with interleukin (IL)-4 (IL4-DCs) or IL-7 (IL7-DCs). Th e cell surface phenotype of GM-CSF-DCs and IL-7-DCs was characterized by a high expression of major histocompatibility complex (MHC) class I and II, C D80, CD86 and CD40. In contrast to 'classical' IL-4-DCs, these two types of DCs expressed CD14 and a CD21-like molecule detected by two out of four CD 21-specific monoclonal antibodies (MoAb) tested. The same pattern of reacti vity with CD21 specific antibodies was observed in freshly isolated adheren t PBMCs but not in B lymphocytes. This reactivity was upregulated by IL-7 i n a dose dependent manner. Lipopolysaccharide (LPS) treatment induced the u pregulation of CD40, CD80, CD86 and the T-cell stimulatory capacity in IL-4 -DCs and, to a lesser extent, in the IL-7-DCs whereas GM-CSF-DCs responded very poorly to such treatment. Our data indicate that, together with GM-CSF , the IL-7 drives macrophage precursors to a differentiation stage that is close to but distinct from the phenotype of IL-4-DCs. Comparison of DC deve lopment in the presence of IL-7 or IL-4 may help in dissecting signalling p athways that regulate the expression of functionally relevant DC markers.