| The exact patho - aetiology of systemic lupus erythematosus ( SLE ) remains elusive. An extremely complicated and multifactorial interaction among various genetic and environmental factors is probably involved. These factors contribute to SLE through three pathways, which are the loss of immune tolerance, dysfunction of immune regulation, and the enhancement of tissue damage.Since T cells play important role in the immune regulation and the production of autoreactive antibodies of IgG class, more and more effort has been made to study the role T cell plays in the pathogenesis of SLE. In fact, studies with SLE patients and SLE murine models have showed various T cell abnormalities, such as the aberrant T cell number, the impairment of inhibitory T cell function, the shifting of cytokine spectrum to Th2 pattern and the loss of self tolerance. An increasing evidence showed abnormal signal transduction and biochemical events in SLE T cells, which were believed to be associated with T cell dysfunction, and phenotype changes. Some signal transduction abnormalities seem to be intrinsic for they exist previous to the emergence of symptoms and are not modified by treatment. Thus, the investigation of the mechanisms leading to these intrinsic T cell defects becomes one of the hot - spots in the field of the stuHy of SLE pathogenesis. Some progresses have been made in searching for the susceptibility loci for abnormal T cell activation and aberrant T cell phenotypes. But the genetic defects in these susceptibility loci remain unknown. So it is necessary to clarify the genetic basis of T cell abnormalities.Lupus -prone mice are useful tools for the studies of SLE. The New Zealand Black ( NZB) strain spontaneously develops autoimmune hemolytic anemia. In addition, a mild form of lupus nephritis can occur in later life of this strain.New Zealand White ( NZW) mice are principally a non - autoimmune strain. In the Fl hybrid progeny of the NZB and NZW strain, florid SUE with a much earlier onset and a higher incidence of nephritis spontaneously develops from a young age onward. It is evident that in (NZB xNZW) Fl mice, NZB -derived genes determine specific aspects of autoimmune phenotypes and that genes from the NZW parent modify the diseases. To investigate the inherited immune abnormalities in Fl mice and determine their susceptibility gene is undoubtedly significant to the study of the pathogenesis of SLE.Studies showed polyclonal T cell activation and aberrant T cell subsets in (NZB xNZW) F1 mice. In order to elucidate whether these T cell abnormalities are related to the genetic background of NZB and NZW and to determine the causing genetic defect, we compared the percentage of T cell subset in the peripheral blood among NZB, NZW and (NZB x NZW) Fl mice and mapped the susceptibility gene of aberrant CD8 + T cell number in ( NZB x NZW) Fl mice by setting up backcross mice model. Based on these results, we selected candidate genes and detected potential defects on these genes by sequencing.Method1. Determination by flow cytometry of the percentage of the CD4+ and CD8 + T cells in the peripheral lymphocytes of mice.Peripheral blood of mice was collected with glass capillary tube from post-bulbar venous plexus and transferred into labeled 12 x 75 mm test tubes in which 0. 5ug FITC - labeled rat - anti - mouse CD8 antibody and 1 ug PE - labeled rat anti - mouse CD4 antibody was added previously. One tube in which FITC - labeled rat IgG2a and PE - labeled rat IgG2a was added was used as negative control. Incubated for 30 minutes at room temperature in the dark cabinet. Then added 2 ml of red cell lysis buffer to each tube. After washing, 500ul 2% formaldehyde was added to each tube to fix the sample. Fluorescence intensity was measured using a FACScan flow cytometer and CellQuest software. Flow cyto-metric analysis utilized linear forward light scatter (FLS) , linear side light scatter (SS) and log fluorescence parameters.2. Gene mapping using genome -wide Quantitative Trait Locus analysis.2. 1 (N...
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