Synergism of nitric oxide and maturation signals on human dendritic cells occurs through a cyclic GMP-dependent pathway

Nitric oxide (NO), generated by phagocytes at inflammation sites, contributes to regulate immune responses through autocrine and paracrine actions on bystander cells. Among the latter are dendritic cells (DCs). Little is known about regulation of DC function by NO, especially in the human system. We exposed human monocyte-derived DCs to the NO donor (z)-1-[2-(2-aminoethyl)-N-(2-ammonioethyl)amino] diazen-1-ium-1,2 diolate (DETA-NO) during their maturation process induced by treatment with tumor necrosis factor alpha or lipopolysaccharide or by CD40 activation. We report here that after exposure to DETA-NO, DCs exhibit a significantly increased ability to activate T lymphocytes stimulated by mycobacterial antigens, Staphylococcus aureus Cowen strain B, allo-antigens, or cross-linking of the CD3-T cell receptor complex. This effect persists after removal of DETA-NO, depends on the generation of cyclic guanosine 5'-monophosphate, and is a result of enhanced release by DCs of soluble factors, in particular interleukin (IL)-12. This modulation of DC function is a result of a synergism between NO and the various maturation stimuli, as neither enhanced T cell activation nor IL-12 release was observed after DC exposure to DETA-NO only. These results provide the first evidence that NO acts as a cosignaling molecule regulating human DC response to maturation stimuli

A method for the analysis of milk and egg allergens for the atopy patch test

The patch test with food antigens (atopy patch test, APT) has been reported as a more specific method than prick or RAST for the early detection of cow's milk and/or egg sensitizations in children. Standardization of APT extracts is a major issue on the road towards full clinical exploitation of this assay. Here, we used sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) to characterize sensitivity and specificity of commercial preparations of APT for milk and egg allergies, which are expected to improve the reliability of this test, when compared with fresh food allergen sources. We found that: (i) SDS-PAGE is an appropriate technique for quality control of APT and (ii) commercial milk and egg APT are equivalent to fresh food preparations in terms of allergen content. Clinical trials aimed at characterizing sensitivity and specificity of APT in the diagnosis of food allergy in children will benefit from this technique

CCR5-reactive antibodies in seronegative partners of HIV-seropositive individuals down-modulate surface CCR5 in vivo and neutralize the infectivity of R5 strains of HIV-1 In vitro

Exposure to HIV does not necessarily results in infection. Because primary HIV infection is associated with CCR5-tropic HIV variants (R5), CCR5- specific Abs in the sera of HIV-seronegative, HIV-exposed individuals (ESN) might be associated with protection against infection. We analyzed sera from ESN, their HIV-infected sexual partners (HIV+), and healthy controls (USN) searching for CCR5-specific Abs, studying whether incubation of PBMC with sera could prevent macrophage inflammatory protein 1\u3b2 (Mip1\u3b2) (natural ligand of CCR5) binding to CCR5. Results showed that Mip1\u3b2 binding to CCR5 was not modified by sera of either 40 HIV+ or 45 USN but was greatly reduced by sera of 6/48 ESN. Binding inhibition was due to Abs reactive with CCR5. The CCR5-specific Abs neutralized the infectivity of primary HIV isolates obtained from the corresponding HIV+ partners and of R5-primary HIV strains, but not that of CXCR4-tropic or amphitropic HIV strains. Immunoadsorption on CCR5-transfected, but not on CXCR4-transfected, cells removed CCR5-specific and virus-neutralizing Abs. Epitope mapping on purified CCR5-specific Abs showed that these Abs recognize a conformational epitope in the first cysteine loop of CCR5 (aa 89-102). Affinity-purified anti-CCR5-peptide neutralized the infectivity of R5 strains of HIV-1. Anti-CCR5 Abs inhibited Mip1\u3b2-induced chemotaxis of PBMC from healthy donors. PBMC from two ESN (with anti-CCR5 Abs) were CCR5-negative and could not be stimulated by Mip1\u3b2 in chemotaxis assays. These results contribute to clarifying the phenomenon of immunologic resistance to HI and may have implications for the development of a protective vaccine

Coseasonal sublingual immunotherapy reduces the development of asthma in children with allergic rhinoconjunctivitis

Abstract BACKGROUND: We wondered whether short-term coseasonal sublingual immunotherapy (SLIT) can reduce the development of asthma in children with hay fever in an open randomized study. OBJECTIVE: We sought to determine whether SLIT is as effective as subcutaneous immunotherapy in reducing hay fever symptoms and the development of asthma in children with hay fever. METHODS: One hundred thirteen children aged 5 to 14 years (mean age, 7.7 years) with hay fever limited to grass pollen and no other clinically important allergies were randomized in an open study involving 6 Italian pediatric allergy centers to receive specific SLIT for 3 years or standard symptomatic therapy. All of the subjects had hay fever symptoms, but at the time of study entry, none reported seasonal asthma with more than 3 episodes per season. Symptomatic treatment was limited to cetirizine, loratadine, nasal budesonide, and salbutamol on demand. The hay fever and asthma symptoms were quantified clinically. RESULTS: The actively treated children used less medication in the second and third years of therapy, and their symptom scores tended to be lower. From the second year of immunotherapy, subjective evaluation of overall allergy symptoms was favorable in the actively treated children. Development of asthma after 3 years was 3.8 times more frequent (95% confidence limits, 1.5-10.0) in the control subjects. CONCLUSIONS: Three years of coseasonal SLIT improves seasonal allergic rhinitis symptoms and reduces the development of seasonal asthma in children with hay fever. Comment in Evid Based Nurs. 2005 Apr;8(2):44