Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.3.4.6 (urease)
 7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

UV irradiation is known to photoisomerize epidermal trans-urocanic acid (trans-UCA) to cis-urocanic acid (cis-UCA), which has been postulated to be involved in local and systemic downregulation of immune responses. We have earlier shown that cis-UCA suppresses interleukin 1 (IL-1) production in human epidermal cells. To study the possible effects of UCA isomers on human peripheral blood lymphoid cells, these cells were cultured in the presence of either UCA stereoisomer, and a number of immunological parameters were assayed. Cis-UCA (100 micrograms/ml) caused a significant downregulation of monocyte IL-1 production, and diminished monocyte HLA-DR expression. Cis-UCA also caused a significant reduction in the CD4/CD8 ratio. Furthermore, T-cells preincubated with cis-UCA caused a significant downregulation of purified protein derivative-induced interleukin 2 production by autologous T-cells. The trans isomer had no effect in any of these in vitro tests. The reported stereospecific effects of cis-UCA are compatible with the postulated function of this chemical as an UV-induced, low-molecular-weight immunomediator substance.
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PMID:Cis-urocanic acid stereospecifically modulates human monocyte IL-1 production and surface HLA-DR antigen expression, T-cell IL-2 production and CD4/CD8 ratio. 263 83

The ability of 23 different strains of Helicobacter pylori to induce proliferative response of human peripheral blood mononuclear cells (PBMC) was investigated. All tested strains stimulated the DNA synthesis of PBMC from both healthy and H. pylori infected blood donors, but with lower stimulation of PBMC of infected donors. Using different bacterial antigen preparations, such as crude membranes, cytoplasmic proteins, and urease, a significantly lower induction of the proliferative response of PBMC from H. pylori infected than from healthy blood donors could also be demonstrated. In contrast to this result the reaction to phytohemagglutinin and purified protein derivative of tuberculin was similar in both groups. The stimulation pathway was interleukin 2 (IL-2) dependent as proved by inhibition of the proliferative response with an alpha-IL-2-receptor antibody. Using an antibody against HLA-DR the lymphoproliferation could also be blocked showing the importance of the major histocompatibility class II (MHCII) complex. Only coincubation of T cells with monocytes plus antigen or with antigen-preincubated monocytes led to a proliferative response showing the necessity of antigen-presenting cells. At least a part of the lymphoproliferative response is MHCII restricted as could be shown with H. pylori specific T-cell lines. These results and the kinetics of the proliferative response with a maximum at day 7 suggest that the proliferative response of human PBMC was mainly induced by antigens than by a mitogen.
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PMID:Stimulatory effects of Helicobacter pylori on human peripheral blood mononuclear cells of H. pylori infected patients and healthy blood donors. 828 Sep 39