Mast cell activation is characterized by upregulation of a functional anaphylatoxin C5a receptor.

Background: Mast cells (MC) are key effector cells of allergic diseases and resistance to helminthic parasites and induce or amplify diverse innate and adaptive immune responses. The signals controlling MC mobilization during inflammation are not fully understood.

Results: Since anaphylatoxins are attractive candidates as MC chemoattractants, we investigated expression and function of anaphylatoxin receptors in murine MC.

TNF controls the infiltration of dendritic cells into the site of Leishmania major infection.

TNF-negative C57BL/6 (B6.TNF(-/-)) mice are highly susceptible to Leishmania (L.) major infection and succumb rapidly to fatal leishmaniasis.

Use of monoclonal antibodies to assess expression of anaphylatoxin receptors in rat and murine models of lung inflammation.

The anaphylatoxins C3a and C5a are involved in the pathophysiology of microbial as well as allergic inflammation in the lungs. Besides their expression in leukocytes, receptors for C3a and C5a (C3aR and C5aR) have been noted in alveolar and bronchial epithelial cells, bronchial smooth muscle cells as well as in vascular endothelial and smooth muscle cells of normal and inflamed human and murine lungs. Recently, however, expression of anaphylatoxin receptors in parenchymal cells of the lung (and kidney) has been challenged.

Use of monoclonal antibodies to assess expression of anaphylatoxin receptors in tubular epithelial cells of human, murine and rat kidneys.

To assess published evidence of anaphylatoxin receptor expression in renal tubular epithelial cells, monoclonal antibodies (mAbs) against human, mouse and rat receptors for C5a and C3a (C5aR, C3aR) were raised using receptor-expressing transfectants as immunogens. Applying these reagents in immunohistochemistry, we observed that mAbs with reactivities against three distinct epitopes of human C5aR N-terminus recognized tissue macrophages but not at all renal tubular epithelial cells. These findings were surprising, as strong tubular staining had been previously demonstrated by mAbs raised against a synthetic N-terminal C5aR peptide.

Functional specialization of memory Th cells revealed by expression of integrin CD49b.

Infection or immunization induces heterogeneous memory T cell subsets, but their origin and protective value against infection are unclear. In this study, we report the functional characterization of two memory Th subsets, defined by expression of integrin CD49b. Stable CD49b expression is induced in up to one-half of all memory Th cells.

CCR7 governs skin dendritic cell migration under inflammatory and steady-state conditions.

The CC chemokine receptor CCR7 has been identified as a key regulator of homeostatic B and T cell trafficking to secondary lymphoid organs. Data presented here demonstrate that CCR7 is also an essential mediator for entry of both dermal and epidermal dendritic cells (DC) into the lymphatic vessels within the dermis while this receptor is dispensable for the mobilization of Langerhans cells from the epidermis to the dermis. Moreover, a distinct population of CD11c(+)MHCII(high) DC showing low expression of the costimulatory molecules CD40, CD80, and CD86 in wild-type animals was virtually absent in skin-draining lymph nodes of CCR7-deficient mice under steady-state conditions.

Analysis of the CCR7 expression on murine bone marrow-derived and spleen dendritic cells.

About 40% of bone marrow-derived dendritic cells (BM-DCs) generated from stem cells of C57BL/6 (B6.WT) mice differentiate in the presence of granulocyte macrophage-colony stimulating factor (GM-CSF) without further stimuli to mature DCs. These cells are characterized by high levels of major histocompatibility complex class II, CD40, and CD86 on their surface.

Anaphylatoxin C5a induces monocyte recruitment and differentiation into dendritic cells by TNF-alpha and prostaglandin E2-dependent mechanisms.

Although monocytes can be directed to develop into dendritic cells (DC) in vitro, the molecular mechanisms that induce their transformation in vivo are largely unknown. In the present study we employed an in vivo SCID mouse model to investigate the impact of two proinflammatory chemotaxins, the anaphylatoxin C5a and the chemokine macrophage inflammatory protein-1alpha (CCL3), on the differentiation of human monocytes and immature DC generated from monocytes in the presence of GM-CSF and IL-4. Both C5a and macrophage inflammatory protein-1alpha recruited human monocytes and immature DC into the peritoneal cavity of SCID mice, but only C5a induced their differentiation into phenotypically mature DC by 48 h after injection.

Characterization of C5aR expression on murine myeloid and lymphoid cells by the use of a novel monoclonal antibody.

The anaphylatoxin C5a is a potent proinflammatory stimulus with immunomodulatory activities. Expression of its receptor C5aR (CD88) has been detected on cells of myeloid origin such as granulocytes and monocytes/macrophages. However, controversial results exist on the expression of C5aR on T and B lymphocytes as well as on mature dendritic cells (DC).

IL-4 down-regulates anaphylatoxin receptors in monocytes and dendritic cells and impairs anaphylatoxin-induced migration in vivo.

Anaphylatoxins mobilize leukocytes to the sites of inflammation. In the present study we investigated the impact of GM-CSF, IL-4, and IFN-gamma on anaphylatoxin receptor expression in monocytes and dendritic cells (DC). IL-4 was identified as the strongest down-regulator of the receptors for C5a and C3a in monocytes and monocyte-derived DC (MoDC).