title: P-glycoprotein functions as a differentiation switch in antigen presenting cell maturation.
abstract: P-glycoprotein (P-gp) expressed on human antigen presenting cells (APC) regulates alloantigen-dependent T-cell activation, but the associated mechanisms are not well understood. Here we demonstrate that P-gp functions in IL-12-dependent monocyte differentiation into dendritic cell (DC) lineages during APC maturation, thereby regulating the capacity of myeloid-derived APCs to elicit alloimmune Th1 responses. Human CD14+ monocytes cultured in vitro in the presence of IL-4/GM-CSF differentiated into CD14(-) CD1A+ APCs of the immature DC phenotype. In contrast, P-gp blockade during differentiation inhibited CD1a induction, down-regulated CD80 expression, enhanced CD86 expression and induced CD68 expression. APCs differentiated in the presence of P-gp blockade stimulated alloimmune T-cell proliferation significantly less than controls and this effect was associated with 97% inhibition of Th1 IFN-gamma production, but preserved Th2 IL-5 secretion. MAb-mediated blockade of the P-gp transport substrate IL-12 in the course of APC differentiation also inhibited IFN-gamma production, while addition of rIL-12 to P-gp-blocked APC differentiation cultures significantly reversed this effect, demonstrating that P-gp functions in APC differentiation in part via IL-12 regulation. Our findings define a novel role for P-gp as a differentiation switch in APC maturation and resultant alloimmune Th1 responses, thereby identifying P-gp as a potential novel therapeutic target in allotransplantation.
authors.affiliation: Transplantation Research Center, Children's Hospital Boston, Massachusetts, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Pendse
authors.forename: S
authors.initials: S
authors.lastname: Behjati
authors.forename: T
authors.initials: T
authors.lastname: Schatton
authors.forename: A
authors.initials: A
authors.lastname: Izawa
authors.forename: M H
authors.initials: MH
authors.lastname: Sayegh
authors.forename: M H
authors.initials: MH
authors.lastname: Frank
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000502:physiology*; D000938:Antigen-Presenting Cells / Q000166:cytology / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D018920:Coculture Techniques; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D008214:Lymphocytes / Q000166:cytology / Q000502:physiology; D012016:Reference Values; D020112:Rhodamine 123 / Q000493:pharmacokinetics; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D020112:Rhodamine 123; D015847:Interleukin-4; D016178:Granulocyte-Macrophage Colony-Stimulating Factor