Objective. Macrophage migration inhibitory factor (MIF) isConclusion. These data represent the first demonstration of the cytokine MIF in human autoimmune disease and suggest MIF as a potential therapeutic target in RA.Macrophage migration inhibitory factor (MIF) is increasingly recognized as an important regulator of immune and inflammatory responses. It is released by activated T lymphocytes and macrophages and upregulates the proinflammatory activity of these cells (1-4). While its original description focused on its ability to prevent the random migration of macrophages in culture, evidence of a broad range of proinflammatory actions continues to emerge. Of note, MIF induces macrophage secretion of tumor necrosis factor ␣ (TNF␣) and promotes interferon-␥ (IFN␥)-induced production of nitric oxide by mouse macrophages (5-7).

The uptake, transport, and presentation of Ags by lung dendritic cells (DCs) are central to the initiation of CD8 T cell responses against respiratory viruses. Although several studies have demonstrated a critical role of CD11blow/negCD103+ DCs for the initiation of cytotoxic T cell responses against the influenza virus, the underlying mechanisms for its potent ability to prime CD8 T cells remain poorly understood. Using a novel approach of fluorescent lipophilic dye-labeled influenza virus, we demonstrate that CD11blow/negCD103+ DCs are the dominant lung DC population transporting influenza virus to the posterior mediastinal lymph node as early as 20 h postinfection. By contrast, CD11bhighCD103neg DCs, although more efficient for taking up the virus within the lung, migrate poorly to the lymph node and remain in the lung to produce proinflammatory cytokines instead. CD11blow/negCD103+ DCs efficiently load viral peptide onto MHC class I complexes and therefore uniquely possess the capacity to potently induce proliferation of naive CD8 T cells. In addition, the peptide transporters TAP1 and TAP2 are constitutively expressed at higher levels in CD11blow/negCD103+ DCs, providing, to our knowledge, the first evidence of a distinct regulation of the Ag-processing pathway in these cells. Collectively, these results show that CD11blow/negCD103+ DCs are functionally specialized for the transport of Ag from the lung to the lymph node and also for efficient processing and presentation of viral Ags to CD8 T cells.

This study identified CD146 as a marker of colony-forming human endometrial stromal cells supporting the concept that human endometrium contains a population of candidate stromal stem/progenitor cells.

Objective. To study the capacity of macrophage migration inhibitory factor (MIF) to regulate proliferation, apoptosis, and p53 in an animal model of rheumatoid arthritis (RA) and in fibroblast-like synoviocytes (FLS) from humans with RA.Methods. Antigen-induced arthritis (AIA) was induced in MIF -/-mice and littermate controls. FLS were obtained from patients with RA. Western blotting and immunohistochemistry were used to measure p53 in cells and tissues. Apoptosis was detected in cells by flow cytometry using TUNEL and annexin V/propidium iodide labeling. Apoptosis in tissue was detected using TUNEL. Proliferation was assessed in cultured cells and tissue by 3 H-thymidine incorporation and Ki-67 immunostaining, respectively.Results. MIF inhibited p53 expression in human RA FLS. Levels of p53 were correspondingly increased in MIF -/-mouse tissues and cells. Spontaneous and sodium nitroprusside-induced apoptosis were significantly increased in MIF -/-cells. In vitro exposure of FLS to MIF reduced apoptosis and significantly induced FLS proliferation. Synoviocyte proliferation in MIF -/-mice was correspondingly reduced. A decrease in the severity of AIA in MIF -/-mice was associated with an increase in p53 and apoptosis in synovium. Evidence of in situ proliferation was scant in this model, and no difference in in situ proliferation was detectable in MIF -/-mice compared with wild-type mice.Conclusion. These results indicate a role for MIF in the regulation of p53 expression and p53-mediated events in the inflamed synovium and support the hypothesis that MIF is of critical importance in the pathogenesis of RA.