Objective To evaluate the significance of serum anti neutrophil cytoplasmic antibodies (ANCAs) and the effects of immune suppressive treatments on its activity in patients with pauci immune crescentic glomerulonephritis (PICGN) Methods Serum ANCAs and myeloperoxidase (MPO) ANCA were detected by indirect immunofluorescence and enzyme linked immuno~sorbent assay (ELISA) methods respectively, and the renal tissues infiltrating cells including CD4 +, CD8 +, CD68 + and PCNA + cells were determined by four layer peroxidase antiperoxidase (PAP) method The clinical manifestations, pathologic features and immune pathologic changes in patients with positive ANCAs were compared with that in patients with negative ANCAs The effects of immune suppressive therapy on clinic and pathologic changes as well as ANCAs activity were also investigated in ANCAs positive and ANCAs negative patients Results Both of clinic active manifestations such as the degree of hematuria, rapidly progressive renal failure and pathologic active features including segmental capillary necrosis and vasculitis were much common in patients with positive ANCAs as compared with that in patients with negative ANCAs The number of infiltrating cells in renal tissue, especially CD4 + cells, was markedly higher in ANCAs positive patients than that in ANCAs negative patients The effects of immune suppressive therapy were also much better in patients with positive ANCAs than that in patients with negative ANCAs Conclusion Serum ANCAs is not only a marker for diagnosis of systemic vasculitis, but also a sensitive predictor for evaluation of diseases’ activity and treatment in patients with PICGN The good effect of immune suppressive treatments on patients with PICGN is partially associated with the degree of ANCAs activity Objective To evaluate the significance of serum anti neutrophil cytoplasmic antibodies (ANCAs) and the effects of immune suppressive treatments on its activity in patients with pauci immune crescentic glomerulonephritis (PICGN) Methods Serum ANCAs and myeloperoxidase (MPO) ANCA were detected by indirect immunofluorescence and enzyme linked immuno-sorbent assay (ELISA) methods respectively, and the renal tissues infiltrating cells including CD4 +, CD8 +, CD68 + and PCNA + cells were determined by four layer peroxidase antiperoxidase (PAP) method The clinical manifestations, pathologic features and immune pathologic changes in patients with positive ANCAs were compared with that in patients with negative ANCAs The effects of immune suppressive therapy on clinic and pathologic changes as well as ANCAs activity were also investigated in ANCAs positive and ANCAs negative patients Results Both of clinic active manifestations such as the the degree of hematuria, rapidly progres sive renal failure and pathologic active features including segmental capillary necrosis and vasculitis were much common in patients with positive ANCAs as compared with that in patients with negative ANCAs The number of infiltrating cells in renal tissue, especially CD4 + cells, was markedly higher in ANCAs positive patients than that in ANCAs negative patients The also of better immune fixed suppressants were also much better in patients with positive ANCAs than that in patients with negative ANCAs Conclusion than in in patients with negative ANCAs than in a marker for diagnosis of systemic vasculitis, but also a sensitive predictor for evaluation of diseases’ activity and treatment in patients with PICGN The good effect of immune suppressive treatments on patients with PICGN is partially associated with the degree of ANCAs activity