Increase in histamine content and enhancement of high affinity IgE receptor FcepsilonRI expression in the human leukemia KU812 cells upon treatment with hydrocortisone

A Practical Electrochemical Nanotool for Facile Quantification of Amino Acids in Single Cell

Though significant advances are made in the arena of single-cell electroanalysis, quantification of intracellular amino acids of human cells remains unsolved. Exemplified by l-histidine (l-His), this issue is addressed by a practical electrochemical nanotool synergizing the highly accessible nanopipette with commercially available synthetic DNAzyme. The fabricated nanotools are screened before operation of a single-use manner, and the l-His-provoked cleavage of the DNA molecules can be sensibly transduced by the ionic current rectification response, the intrinsic property of nanopipette governed by its interior surface charges. Regional distribution of cytosolic l-His level in human cells is electrochemically quantified for the first time, and time-dependent drug treatment effects are further revealed. This work unveils the possibility of electrochemistry for quantification of cytosolic amino acids of a spatial- and time-based manner and ultimately enables a better understanding of amino acid-involved events in living cells.

Construction of an in vitro allergy reaction evaluation system using human leukemia cell lines

Human leukemia cell lines, KU812 and KU812F, are immature prebasophillic cell lines and have a potential to differentiate into basophils. Hydrocortisone (HC) and sodium nitroprusside (SNP) can enhance the cell surface FcepsilonRI expression of KU812 cells. However, the differentiated phenotypes of KU812 cells were unstable, hindering the application of KU812 cells to construct a practical invitro allergy reaction evaluation system. Here, we attempted to enhance the cell surface expression of FcepsilonRI on hydrocortisone (HC)- or sodium nitroprusside (SNP)-treated KU812 cells by IgE. The cell surface FcepsilonRI expression was observed in about 20, 20 and 26% of 1 muM HC-, 1 nM SNP- and 450 ng ml(-1) IgE-treated KU812 cells, respectively. Whereas, the cell surface FcepsilonRI expression was observed in about 54% of KU812 cells treated with both 450 ng ml(-1) IgE and 1 muM HC for 8 days, and in about 33% of KU812 cells treated with both 450 ng ml(-1) IgE and 1 nM SNP for 4 days. Ninety five% of the IgE/HC- or IgE/SNP-treated KU812 cells expressed CD 13 antigen, a cell surface marker of basophils. An electrophoretic mobility shift assay revealed that AP-1, NF-AT and NF-kappaB transcription factors were all activated in IgE/HC- and IgE/SNP-treated KU812 cells. Since the differentiated KU812F cells were more sensitive than KU812 cells for histamine release by sensitization with human IgE and anti-IgE antibody, a practical in vitro allergy reaction evaluation system for general use was constructed using IgE/HC-treated KU812F cells. The differentiated KU812F cells sensitized with an allergicpatient's IgE and mite allergen exhibited histamine release. The constructed in vitro allergy reaction evaluation system using differentiated human leukemia KU812F cells will be useful to study allergic reaction and to analyze physiologically functional substances in allergic disease.