Relationship between serum B-cell activating factor levels and clinicopathology in children with lupus nephritis

Objective To analyze the relationship between the serum B-cell activating factor (BAFF) levels and clinical characters and pathological features in children with lupus nephritis (LN). Methods ELISA was used to detect the serum BAFF (sBAFF) levels of the 54 LN children diagnosed in the First Affiliated Hospital, Sun Yat-sen University during October 1, 2014 to December 31, 2016 and with complete clinical data. According to whether glucocorticoid or immunosuppressive agents has been used at their first admission, patients were divided into treated group (n=44) and non-therapy group (n=10). According to the renal response after induction treatment for 6 months, patients were divided into remission group (n=20) and non-response group (n=34). According to whether there was renal recurrence, they were divided into recurrence group (6 cases) and non-recurrence group (48 cases). According to renal biopsy, patients were divided into class-Ⅲ, class-Ⅳ and class-Ⅴ group. Another 15 healthy children were taken as a control group. The correlations between sBAFF and clinical manifestation, laboratory examination, renal biopsy and clinical outcome were analyzed. Results (1) Compared with the control group, the sBAFF was significantly increased in LN group (t=3.821, P<0.001). Compared with the non- neuropsychiatric systemic lupus erythematosus (NPSLE) group, sBAFF was significantly increased in NPSLE group (t=2.202, P=0.032). (2) Compared with that in treated group, sBAFF was significantly higher in untreated group (LSD-t=2.309, P=0.025). Compared with non-response group, sBAFF was significantly decreased in response group (LSD-t=2.035, P=0.046). (3) No significant difference was observed between class-Ⅲ, class-Ⅳ and class-Ⅴ pathological classification group (F=1.080, P=0.459). sBAFF in LN children was not significantly correlated with the active index (AI) or chronic index (CI) of Austin index (r=-0.273, P=0.063; r=0.150, P=0.314). (4) In LN children, sBAFF has positive correlation with ESR and IgG level (r=0.289, P=0.036; r=0.340, P=0.017) and negative correlation with WBC (r=-0.337, P=0.013). Multiple linear regression model showed that serum IgG level (β'=0.517, P=0.001) and renal response (β'=-0.271, P=0.037) were independent influencing factors of sBAFF level. Conclusions Renal remission and serum IgG levels in LN children are influencing factors of sBAFF levels. sBAFF is helpful to clinical assessment on renal response of LN children. Key words: B-cell activating factor; Lupus erythematosus, systemic; Lupus nephritis; Child; Clinical manifestation; Remission