Background B lymphocytes infiltration associated ectopic lymphoid tissue (ELT) formation in situ kidney tissue had been showed to play an important role in the pathogenesis of MRL/lpr lupus nephritis mice model, until now there are few studies to identify the significance of them in the pathogenesis, diagnosis and treatment of human lupus nephritis (LN).

Objectives To know the significance of B lymphocytes infiltration and associated ectopic lymphoid tissue (ELT) formation in the pathogenesis, diagnosis and treatment of human LN

Methods The renal specimen were analyzed by light microscopy examination of routine pathology and immunohistochemistry detection of CD3+,CD20+ and CD21+ cells expression. The enrolled patients were grouped based on the WHO classification of pathology or ELT patterns. Clinical datawere collected and evaluated.

Results 89 LN patients were experienced with GC and IS combination therapy and WHO III 21, WHO IV 53 and WHO V 15. 69 cases of CD20+ cells group and 20 of CD20-cells group could be divided. comparing to CD20-group, no difference could be founded in age, sex, blood leucocytes, urine protein, C3 level, C4 level, ESR, CRP, antiDNA, acute injury index and chronic injury index of renal tissue and total remission rate (all P>0.05), but significant difference can be found in mean disease duration (CD20+group: 21.8±9.9 months VS CD20-group: 9.8±6.2 months) (P=0.045) and complete disease remission rate (CD20+group: 63.8% VS CD20-group: 90%) (P=0.047) at 6 month of treatment. With respect to B lymphocytes infiltration associated ELT formation, there was focal distribution of CD3+ T cells and CD20+B cells (type 2) in 51 cases (57.3%), scattering distribution of CD3+ T cells and CD20+B cells (type 1) in 18 cases (20.2%) and no CD20+B cells infiltration in 20 cases (22.5%) but no expression of CD21+ dendritic cells expression in all. There was longer disease duration in type 2 patients than in type 1 or type 0 patients. compared to WHO V-LN patients, there was different ELT distribution patterns in WHO III and WHO IV-LN patients, but there were no difference in ELT distribution patterns between WHO III and WHO IV-LN patients.

Conclusions Focal distribution of CD3+ T cells and CD20+B cells (type 2 ELT)was main pattern in the renal interstitial tissue of LN patients. B cells infiltration-associated ELT formation is a predictor of longer disease duration and poor response to conventional combination therapy of high-dose GC and IS.

Acknowledgement Acknowledgement to pathologist professor Ping Mei and the statistian He Li

Disclosure of Interest None declared