Altered immune parameters correlate with infection-related hospitalizations in children with Down syndrome.

In addition to previously studied immunological variables, the relative expression of IFNGR2, IFNAR1, CD18, and CD275 (all encoded in chromosome 21) on circulating leucocytes and multifunctional T cells (evaluated by an intracellular cytokine/proliferation assay) were compared between children with Down syndrome (DS) and healthy controls (HC). As previously reported, numbers of lymphocytes, CD4(+) T cells, Treg cells, B cells, and levels of serum IgM were decreased, and levels of IgG and IgA were increased in children with DS. Moreover, the relative expression of CD18 on T and B cells (previously and not previously reported, respectively) were elevated in DS children (p⩽0.01). Age and numbers of B and Treg cells moderately correlated with retrospectively identified infection related hospitalizations (rho: 0.300-0.460, p⩽0.003). Age and the numbers of Treg cells also correlated with prospectively identified infection related hospitalizations. Future studies are necessary to clarify the role of these parameters in the immunity of DS patients.

Photopatch testing in Bogota (Colombia): 2011-2013.

BACKGROUND: Photopatch tests are used to diagnose photoallergic contact dermatitis and identify the causal agents. The frequencies of positive results and associated allergens vary by country; therefore, it is necessary to know the information specific to each country. OBJECTIVE: To establish the frequency of positive photopatch test results, and their relevance, in patients with suspected photoallergic contact dermatitis in a national dermatology centre located in Bogota, Colombia. MATERIALS AND METHODS: One hundred patients investigated for possible photoallergic contact dermatitis were enrolled in the study. They were photopatch tested with a selected group of allergens, and occluded for 48 hours; the duplicate right-hand panel was irradiated with 5 J/cm(2) ultraviolet (UV)A. The readings were performed on day (D)2, D4, and D6, in accordance with the guidelines of the ICDRG, and the relevance was evaluated with the COADEX system. RESULTS: There were a total of 20 photopatch reactions in 15 patients, 95% of which were caused by UV filters, most frequently benzophenone-3 (55%). Eight of the positive reactions (53.3%) appeared on D6. CONCLUSIONS: UV filters continue to be the most common causes of photoallergic contact dermatitis in our patients. Readings up to D6 (96 h after irradiation) are important to identify delayed positive reactions.

Circulating rotavirus-specific T cells have a poor functional profile.

Frequencies of circulating T cells producing IFN-γ, TNF-α, and IL-2, and percentages of T cells proliferating after stimulation with rotavirus (RV), tetanus toxoid, and influenza were evaluated in PBMC derived from healthy adults and children. In addition, the potential anergic state of RV-specific T cells was analyzed by stimulation of PBMC with RV antigen in the presence of three anergy inhibitors (rIL-2, rIL-12, or DGKα-i). The quality and magnitude of RV-T cell responses were significantly lower than those of tetanus toxoid and influenza antigens. RV-CD4 T cell response was enriched in monofunctional IFN-γ(+) cells, while influenza-CD4 and tetanus toxoid-CD4 T cell responses were enriched in multifunctional T cells. Moreover, rIL-2--unlike rIL-12 or DGKα-i--increased the frequencies of RV-CD4 TNF-α(+), CD4 IFN-γ(+), and CD8 IFN-γ(+) cells. Thus, circulating RV-T cells seem to have a relatively poor functional profile that may be partially reversed in vitro by the addition of rIL-2.

Non-dermatophyte mould onychomycosis: a clinical and epidemiological study at a dermatology referral centre in Bogota, Colombia.

Worldwide prevalence of non-dermatophyte mould onychomycosis has increased in recent years; however, available information on the topic is confusing and oftentimes contradictory, probably due to the small number of reported cases. The aim of this study was to determine and describe the aetiological agents, as well as the epidemiological and clinical characteristics of non-dermatophyte mould onychomycosis in a dermatology referral centre in Bogota, Colombia. A cross-sectional descriptive study was conducted between January 2001 and December 2011 among patients who attend the National Institute of Dermatology with a confirmed diagnosis of onychomycosis by non-dermatophytes moulds. There were 317 confirmed cases of non-dermatophyte mould onychomycosis in 196 women and 121 men whose average age was 43 years. Twenty-seven per cent of them had a history of systemic disease. The habit of walking and showering barefoot was the major infection-related factor. Distal and lateral subungual presentation was the most common pattern of clinical presentation. The most frequent non-dermatophyte mould was Neoscytalidium dimidiatum followed by Fusarium spp. No relationship was observed with predisposing factors previously reported in the literature. Clinical features found in this population are indistinguishable from onychomycosis caused by dermatophytes. High prevalence of N. dimidiatum found here was in contrast to a large number of studies where other types of moulds predominate.

A TGF-beta mediated regulatory mechanism modulates the T cell immune response to rotavirus in adults but not in children.

Children with acute RV-gastroenteritis (GE) had low or undetectable levels of circulating IFN-gamma(+), IL-13(+), IL-2(+), IL-10(+) or IL-17(+) RV-T cells. IFN-gamma(+) T cells and low frequencies of IL-10(+) and IL-2(+) CD4(+) T cells were found in adults with RV-GE during acute and convalescence phases, respectively. Circulating single IFN-gamma(+)>double IFN-gamma(+)/IL-2(+)>single IL-2(+)RV-CD4(+)T cells were observed in healthy adults. In this group, frequencies of IFN-gamma(+) RV-T cells increased after removing CD25(+)cells, blocking TGF-beta with its natural inhibitor, LAP, or inhibiting TGF-betaRI signalling pathway with ALK5i. The frequencies of IFN-gamma(+) RV-T cells were also incremented in PBMC depleted of CD25(+)cells and treated with ALK5i, suggesting that TGFbeta inhibition may be independent of Treg cells. The ALK5i effect was observed in adults but not in children with RV-GE, who had normal numbers of TGF-beta+ Treg cells. Thus, a TGF-beta-mediated regulatory mechanism that modulates RV-T cells in adults is not evident in children.

Interaction of rotavirus with human peripheral blood mononuclear cells: plasmacytoid dendritic cells play a role in stimulating memory rotavirus specific T cells in vitro.

We studied the interaction of RV with human peripheral blood mononuclear cells (PBMC) from adult volunteers. After exposure of PBMC to rhesus RV (RRV), T and B lymphocytes, NK cells, monocytes, and myeloid and plasmacytoid dendritic cells expressed RV non-structural proteins, at variable levels. Expression of these RV proteins was abolished if infection was done in the presence of anti-VP7 neutralizing antibodies or 10% autologous serum. Supernatants of RRV exposed PBMC contained TNF-alpha, IL-6, IFN-alpha, IFN-gamma, IL-2 and IL-10. Plasmacytoid DC were found to be the main source of IFN-alpha production, and in their absence the production of IFN-gamma and the frequency of RV specific T cells that secrete IFN-gamma diminished. Finally, we could not detect RV-antigen associated with the PBMC or expression of RV non-structural proteins in PBMC of acutely RV-infected children. Thus, although PBMC are susceptible to the initial steps of RV infection, most PBMC of children with RV-gastroenteritis are not infected.