Macrophage inflammatory protein 3alpha is involved in the constitutive trafficking of epidermal langerhans cells.

Certain types of dendritic cells (DCs) appear in inflammatory lesions of various etiologies, whereas other DCs, e.g., Langerhans cells (LCs), populate peripheral organs constitutively. Until now, the molecular mechanism behind such differential behavior has not been elucidated. Here, we show that CD1a(+) LC precursors respond selectively and specifically to the CC chemokine macrophage inflammatory protein (MIP)-3alpha. In contrast, CD14(+) precursors of DC and monocytes are not attracted by MIP-3alpha. LCs lose the migratory responsiveness to MIP-3alpha during their maturation, and non-LC DCs do not acquire MIP-3alpha sensitivity. The notion that MIP-3alpha may be responsible for selective LC recruitment into the epidermis is further supported by the following observations: (a) MIP-3alpha is expressed by keratinocytes and venular endothelial cells in clinically normal appearing human skin; (b) LCs express CC chemokine receptor (CCR)6, the sole MIP-3alpha receptor both in situ and in vitro; and (c) non-LC DCs that are not found in normal epidermis lack CCR6. The mature forms of LCs and non-LC DCs display comparable sensitivity for MIP-3beta, a CCR7 ligand, suggesting that DC subtype-specific chemokine responses are restricted to the committed precursor stage. Although LC precursors express primarily CCR6, non-LC DC precursors display a broad chemokine receptor repertoire. These findings reflect a scenario where the differential expression of chemokine receptors by two different subpopulations of DCs determines their functional behavior. One type, the LC, responds to MIP-3alpha and enters skin to screen the epidermis constitutively, whereas the other type, the "inflammatory" DC, migrates in response to a wide array of different chemokines and is involved in the amplification and modulation of the inflammatory tissue response.

A standardized, a computer-assisted in vitro assay for the assessment of neutrophil transmigration across endothelial monolayers.

We describe an automated, observer-independent and highly reproducible assay for the quantification of transmigrated neutrophils across endothelial monolayers. Endothelial cells grown on collagen gels were loaded with a dye emitting red fluorescence. Neutrophils loaded with dye emitting green fluorescence were allowed to adhere to and transmigrate across endothelial monolayers. For quantification of adherent and migrated cells, randomly selected fields were scanned by confocal laser scan microscopy at defined depths within and below the endothelial monolayers. The images obtained were transferred into the public domain NIH image program and numbers and distribution of cells within scanned sectors were automatically calculated. We demonstrate that adherent neutrophils are easily discriminated from transmigrated cells; absolute numbers of migrated cells can be reproducibly calculated by counting cells at a depth of -20 microm, thus permitting evaluation of large-scale experiments: the efficacy of neutrophil transmigration depends on the level of endothelial activation after TNF stimulation and mAbs to cell surface adhesion molecules interfere with migration in a manner similar to that previously shown in in vivo experiments. This assay lends itself to the identification of molecules influencing in cell migration in each phase of EC activation and to the screening of pro- and anti-migratory properties of biological or pharmacological reagents.

The association of smoking with IGRA and TST results in HIV-1-infected subjects.

OBJECTIVE: To assess the association of smoking with the interferon-gamma (IFN-γ) release assay and tuberculin skin test (TST) results in a comparative study on the detection of latent tuberculous infection (LTBI) in human immunodeficiency virus (HIV) 1-infected individuals. METHODS: In this cross-sectional study, 305 HIV-1-infected subjects were tested by the QuantiFERON-TB Gold In-Tube assay (QFT-GIT) and the TST. We evaluated the impact of smoking and other LTBI risk factors on QFT-GIT and TST results. RESULTS The concordance of both tests was 93% (κ = 0.71, P < 0.001). The following independent risk factors for both QFT-GIT and TST positivity were identified: birth in a high TB incidence country, self-reported contact with an active TB case and elevated CD4(+) T-cell count (P < 0.001). While smoking was not independently associated with a positive QFT-GIT (OR 1.2, 95%CI 0.5-2.8) or TST result (OR 1.8, 95%CI 0.6-5.9), there was an inverse correlation of the number of cigarettes smoked with IFN-γ levels measured using QFT-GIT (ρ = -0.14, P = 0.027). In addition, smoking was independently associated with a quantitative QFT-GIT response in linear regression analysis (ß = 0.129, P = 0.025). CONCLUSIONS: Although smoking may have a minor inhibitory effect on QFT-GIT response, QFT-GIT results seem not to be affected by smoking to a clinically significant extent.

Survival, maturation, and function of CD11c- and CD11c+ peripheral blood dendritic cells are differentially regulated by cytokines.

Two types of dendritic cells (DC) are circulating in human blood and can be identified by their differential expression of the myeloid Ag CD11c. In this study, we show that CD11c- peripheral blood (PB)-DC correspond to plasmacytoid DC of lymphoid tissue not only by their surface Ag expression profile but, more impressively, by their peculiar ultramorphology. We also demonstrate that CD11c- and CD11c+ DC differ in the quality of their response to and in their requirement for certain cytokines. Freshly isolated CD11c- cells depend on IL-3 for survival and use autocrine or exogenous TNF-alpha as maturation signal, leading to the appearance of a highly dendritic phenotype, the up-regulation and redistribution of MHC class II from lysosomal compartments to the plasma membrane, the increased expression of costimulatory molecules, and the switch from a high Ag-processing to a low Ag-processing/potent accessory cell mode. Surprisingly, IL-4 efficiently killed freshly isolated CD11c- PB-DC, but did not impair the viability of CD11c+ PB-DC and, together with GM-CSF, induced maturation of these cells. A direct functional comparison revealed that neo-Ag-modified and subsequently matured CD11c- but to a lesser extent CD11c+ DC were able to prime naive Ag-specific CD4+ T cells. Our findings show that two diverse DC types respond to certain T cell-derived cytokines in a differential manner and, thus, suggest that suppression or activation of functionally diverse DC types may be a novel mechanism for the regulation of the quantity and quality of immune responses.