Lorant Farkas

University of Oslo

Background: Thymic stromal lymphopoietin (TSLP) controls allergic TH2 inflammatory responses through induction of distinct activation programs in dendritic cells (DCs). However, knowledge about TSLP receptor expression and functional consequences of receptor activation by DCs residing in the human respiratory tract is limited. Objective: We want...

It has been suggested that allergic diseases are caused by defective suppression of allergen-specific Th2 cells by CD4(+)CD25(+) regulatory T cells. However, such studies have been hampered by the difficulty in distinguishing regulatory T cells from CD25-expressing activated T cells. Recently, it was shown that conventional T cells expressed high l...

Dendritic cells (DCs) are believed to regulate T cell-mediated immunity primarily by directing differentiation of naive T cells. Here, we show that a large fraction of CD4(+) memory cells produce IL-10 within the first hours after interaction with plasmacytoid DCs (PDCs). In contrast, CD11c(+) DCs induce IFN-gamma and little IL-10. IL-10-secreting...

In recent years, the study of systemic lupus erythematosus (SLE) patients has revealed a central role for type I interferon (IFN) in disease pathogenesis. IFN induces the unabated activation of peripheral dendritic cells, which select and activate autoreactive T cells rather than deleting them, thus failing to induce peripheral tolerance. IFN also...

Inherent properties of dendritic cell (DC) subsets are important in the regulation of naïve T-cell differentiation (e.g. Th1 versus Th2 cells), whereas effector memory T cells are believed to produce a fixed cytokine repertoire independent of the type of antigen presenting cell. Here we show that two distinct human DC subsets, plasmacytoid DC (PDC)...

It has been suggested that human cytomegalovirus (HCMV) evades the immune system by infecting and paralyzing antigen-presenting cells. This view is based mainly on studies of dendritic cells (DCs) obtained after culture of monocytes (moDCs). It is contradicted by the asymptomatic course of HCMV infection in healthy persons, indicating that other ke...

The hygiene hypothesis implies that the increasing prevalence of allergy in 'westernized' countries is explained by reduced bacterial exposure in early life, but the underlying mechanism remains elusive. We therefore wanted to study the effect of bacterial lipopolysaccharide (LPS) on the generation of regulatory T (T(R)) cells in neonates, and to a...

Plasmacytoid dendritic cells (PDCs) accumulate in the nasal mucosa of allergic rhinitis patients, but their function in upper airway allergy has not been determined. CpG oligodeoxynucleotides, potent adjuvants in immunotherapeutic strategies in animal models, are especially effective at activating PDCs. These cells are therefore potential targets f...

In vitro studies have reported that plasmacytoid dendritic cells (PDCs) exert multiple functions, including production of interferon (IFN)-alpha as effector cells and regulation of T-cell responses as mature DCs. Here we review recent data obtained in situ showing that PDCs accumulate in lesions of type I IFN-related disorders (virus infections and...

Plasmacytoid dendritic cell (P-DC) precursors in peripheral blood produce large amounts of interferon (IFN)-alpha/beta when triggered by viruses. However, when incubated with interleukin-3 and CD40 ligand, the same precursors differentiate into mature DCs that stimulate naïve CD4(+) T cells to produce Th2 cytokines. We recently reported that P-DCs...

Recent evidence suggests that the previously enigmatic cell type designated plasmacytoid monocytes can function as dendritic cells and contribute substantially to both innate and adaptive immunity. This cell type has previously been described only in bone marrow, blood, and organized lymphoid tissue, but not at effector sites with direct Ag exposur...

Ca2+ entry through the capacitative (store-regulated) pathway was shown to be inhibited in neutrophil granulocytes by the protein kinase C activator phorbol 12-myristate 13-acetate and the chemoattractantN-formyl-methionyl-leucyl-phenylalanine (fMLP) by a hitherto unknown mechanism. Measuring both Ca2+ and Mn2+ entry into store-depleted cells we sh...