Cytomegalovirus-induced cutaneous microangiopathy manifesting as lower limb ischemia in a human immunodeficiency virus-infected patient

Cutaneous infections by cytomegalovirus (CMV) are rare and often difficult to diagnose both clinically and histopathologically. A wide range of different clinical manifestations have been described in the literature, especially in immunosuppressed patients. CMV-induced thrombosis has also been reported in these patients, and various mechanisms have been proposed to explain the role of CMV in the thrombotic process, including direct damage of the endothelial cells, activation of coagulation factors and inducing the production of antiphospholipid antibodies. We present the case of a human immunodeficiency virus (HIV)-infected woman who developed distal ischemic lesions of the lower extremities during a generalized CMV infection. We discuss the role of CMV and antiphospholipid antibodies in the pathogenesis of thrombosis in immunosuppressed patients.     

Candida albicans-specific lymphoproliferative and cytokine (IL-4 and IFN-gamma) responses in atopic eczema dermatitis syndrome. Evidence of CD4/CD8 and CD3/CD16+CD56 ratio elevations in vitro

BACKGROUND: Hypersensitivity to cross-reactive mannan polysaccharide allergens of saprophytic yeasts is likely to be involved in the pathogenesis of atopic eczema dermatitis syndrome (AEDS). Mannans induce elevated specific immunoglobulin E and lymphoproliferative responses in peripheral blood mononuclear cells (PBMCs). To gain more detailed data of the involvement of different subpopulations of PBMCs in AEDS after mannan stimulation, changes in the cell-surface marker distribution were analysed. METHODS: The Ficoll-isolated PBMCs of eight yeast hypersensitive AEDS patients and seven non-AEDS controls were stimulated in vitro by mannan (CAM) or whole extract antigen [In-House Reference (IHR)] of Candida albicans or tuberculin [purified protein derivative (PPD)] and after immunofluorescence staining analysed by flow cytometry. The expression of cytokine mRNA was measured by kinetic real-time polymerase chain reaction (TaqMan). RESULTS: After 7-day antigen stimulation, there were significant increases in the CD3/CD16(+)CD56 ratio (P = 0.028 with mannan and P = 0.006 with IHR), CD4/CD8 ratio (P = 0.049 with mannan) and interleukin-4/interferon-gamma (IL-4/IFN-gamma) mRNA ratio (P = 0.028 with IHR) and a decrease in the CD3/CD19 ratio (P = 0.035 with mannan) of AEDS patients' PBMCs as compared with healthy controls' cells. These changes were not seen in cultures with PPD. CONCLUSIONS: The observed CAM and IHR-induced elevations in T cell/natural killer cell, CD4/CD8 and IL-4/IFN-gamma ratios suggest that C. albicans-induced TH(2)-type responses can also play a role in AEDS.     

In situ depletion of CD4<Superscript>+</Superscript> T cells in human skin by Zanolimumab

CD4⁺ T cells, in activated or malignant form, are involved in a number of diseases including inflammatory skin diseases such as psoriasis, and T cell lymphomas such as the majority of cutaneous T cell lymphomas (CTCL). Targeting CD4 with an antibody that inhibits and/or eliminates disease-driving T cells in situ may therefore be a useful approach in the treatment of inflammatory and malignant skin diseases. Depletion of CD4⁺ T cells in intact inflamed human skin tissue by Zanolimumab, a fully human therapeutic monoclonal antibody (IgG1, κ) against CD4, was studied in a human psoriasis xenograft mouse model. Zanolimumab treatment was shown to induce a significant reduction in the numbers of inflammatory mononuclear cells in upper dermis. This reduction in inflammatory mononuclear cells in situ was primarily due to a significant reduction in the numbers of skin-infiltrating CD4⁺, but not CD8⁺ CD3⁺ T cells. The capacity of Zanolimumab to deplete the CD4⁺ T cells in the skin may be of importance in diseases where CD4⁺ T cells play a central role. Indeed, in a phase II clinical trial Zanolimumab has shown a dose-dependent clinical response in patients with CTCL and the antibody is currently in a phase III clinical trial for CTCL, a disease for which there is no safe and effective treatment available today.     

Functional characterization of CD4+CD25+ regulatory T cells differentiated in vitro from bone marrow-derived haematopoietic cells of psoriasis patients with a family history of the disorder

BACKGROUND: In psoriasis CD4+CD25+ regulatory T cells are functionally deficient. The imbalance between regulatory and effector T-cell functions is important for inducing psoriasis. It is reasonable to speculate that the dysfunctional activity of CD4+CD25+ regulatory cells may originate partly from the abnormal haematopoietic cells determined mainly by genetic background. OBJECTIVES: To test the hypothesis that haematopoietic stem cells are responsible for dysfunctional CD4+CD25+ regulatory cells in psoriasis. METHODS: Bone marrow-derived CD34+ haematopoietic cells from patients with psoriasis (with a family history of psoriasis) and from normal controls were differentiated into T cells in vitro. CD4+CD25+ T cells were isolated by an immunomagnetic bead method, and proliferation activity and capacity for cytokine secretion were determined. Furthermore, the ability of CD4+CD25+ T cells to suppress the proliferative responses of allogeneous peripheral blood CD4+CD25- effector T cells was assessed in vitro. RESULTS: The differentiated CD4+CD25+ T cells of psoriatic origin showed similar characteristics to those of normal volunteers, including proliferation activity and secretion profile of the cytokines interleukin (IL)-2, IL-4, IL-8, IL-10 and interferon (IFN)-gamma. However, proliferation and secretion levels of the cytokines IL-2 and IL-10 for CD4+CD25+ cells of psoriatic CD34+ cell origin were significantly lower than those of normal controls in response to streptococcal superantigen (Strep-A). In particular, CD4+CD25+ T cells differentiated from psoriatic CD34+ cells were functionally insufficient to restrain effector T-cell proliferation. CONCLUSIONS: CD4+CD25+ T cells differentiated in vitro from haematopoietic cells of patients with psoriasis are impaired in regulatory function. The dysfunction of psoriatic CD4+CD25+ T cells may be due to inherent genetic programming passed down from bone marrow-derived haematopoietic cells.     

Recombinant,ETA′‐based CD64 immunotoxins: improved efficacy by increased valency,both in vitro and in vivo in a chronic cutaneous inflammation model in human CD64 transgenic mice

Background Dysregulated, activated macrophages play a pivotal role in chronic inflammatory diseases such as arthritis and atopic dermatitis. These cells display increased expression of the high‐affinity Fcγ receptor (CD64), making them ideal targets for CD64‐specific immunotoxins. We previously showed that a chemically linked immunotoxin, the monoclonal H22‐RicinA, specifically eliminated infiltrating activated macrophages and resolved chronic cutaneous inflammation. However, several disadvantages are associated with classic immunotoxins, and we therefore followed a fusion protein strategy to express the antigen‐binding site alone (scFv H22) fused to a derivative of Pseudomonas exotoxin A (ETA′). Objectives To assess the potential effect of increased valency on efficacy, we produced monovalent [H22(scFv)‐ETA′] and bivalent [H22(scFv)₂‐ETA′] versions and evaluated their potential for eliminating activated macrophages both in vitro and in vivo. Methods Both immunotoxins were produced by bacterial fermentation. Binding was assessed by flow cytometry on the monocytic CD64+ cell line U937. Toxicity was analysed by XTT and apoptosis induction by annexin V bioassay. The in vivo effect was tested in a human CD64 transgenic mouse model for cutaneous inflammation. Results The cytotoxic effects of both immunotoxins were clearly due to apoptosis with an IC₅₀ of 140 pmol L^?1 for monovalent and only 14 pmol L^?1 for the divalent version. In vivo treatment with H22(scFv)‐ETA′ reduced CD64+ activated macrophages to 21% of their initial numbers whereas H22(scFv)₂‐ETA′ treatment reduced these cells to 4·8% (P < 0·001). Conclusions These data clearly show increased efficacy due to increased valency of the anti‐CD64 immunotoxin. Both recombinant immunotoxins have a low IC₅₀, making them suitable for the treatment of diseases involving dysregulated, activated macrophages.