Multiprotein Adsorption from Human Serum at Gold and Oxidized Iron Surfaces Studied by Atomic Force Microscopy and Polarization-Modulation Infrared Reflection Absorption Spectroscopy.

Multiprotein adsorption from complex body fluids represents a highly important and complicated phenomenon in medicine. In this work, multiprotein adsorption from diluted human serum at gold and oxidized iron surfaces is investigated at different serum concentrations and pH values. Adsorption-induced changes in surface topography and the total amount of adsorbed proteins are quantified by atomic force microscopy (AFM) and polarization-modulation infrared reflection absorption spectroscopy (PM-IRRAS), respectively. For both surfaces, stronger protein adsorption is observed at pH 6 compared to pH 7 and pH 8. PM-IRRAS furthermore provides some qualitative insights into the pH-dependent alterations in the composition of the adsorbed multiprotein films. Changes in the amide II/amide I band area ratio and in particular side-chain IR absorption suggest that the increased adsorption at pH 6 is accompanied by a change in protein film composition. Presumably, this is mostly driven by the adsorption of human serum albumin, which at pH 6 adsorbs more readily and thereby replaces other proteins with lower surface affinities in the resulting multiprotein film.

[Levels of regulatory T cells in peripheral blood of children with idiopathic thrombocytopenic purpura].

OBJECTIVE: To study the levels of CD4+CD25+CD127- and CD3+CD4-CD8- regulatory T (Treg) cells in peripheral blood of children with idiopathic thrombocytopenic purpura (ITP). METHODS: The flow cytometry was used to detect the expression of CD4+CD25+CD127- and CD3+CD4-CD8- Treg cells in peripheral blood of 33 children with ITP and 21 healthy children. RESULTS: The expression levels of CD4+CD25+CD127-ï¼»(2.7±1.7)% vs (4.8±1.6)%; P<0.01ï¼½and CD3+CD4-CD8-ï¼»(5.2±3.1)% vs (8.1±3.5)%; P<0.01ï¼½Treg cells in children with ITP were significantly lower than in the controls. CONCLUSIONS: The expression levels of CD4+CD25+CD127- and CD3+CD4-CD8- Treg cells decrease in children with ITP, suggesting that CD4+CD25+CD127- and CD3+CD4-CD8- Treg cells might play a role in the pathogenesis of ITP.