AIMTo investigate the significance of the calcineurin (CaN) activation in active lupus nephritis patient.

METHODSPeripheral blood mononuclear cells (PBMCs) were separated from twenty-one active LN patients and 12 healthy controls. Phosphatase activity of CaN was determined using the CaN assay kit by measuring the content of released PO4. Reverse transcription-PCR was used to detect the expression of CD40L mRNA. Flow cytometry analysis was used to detect the expression of CD40L in LN PBMC.

RESULTS(1) Increased activation of CaN in spontaneous cultured PBMC in active LN group was found as compared with control group (46.08 +/- 5.58 vs 8.81 +/- 3.61, P < 0.01). In stimulated by PMA/Ionomycin , activity of CaN in active LN group was also higher than that of control (69.34 +/- 12.59 vs 37.12 +/- 11.57, P < 0.01). (2) Relative content of CD40L in PBMC in active LN groups increased significantly as compared with the control groups under spontaneous and PMA/Ionomycin-induced culture, respectively (P < 0.01). (3) FK506 reduced significantly production of CD40L in spontaneous and PMA/Ionomycin-induced PBMC of LN.

CONCLUSIONElevated activation of CaN in active LN may participate in regulation overexpression of CD40L in PBMC of LN. Through inhibiting CaN activity, FK506 may prevent abnormal activation of CD40-CD40L costimulatory pathway in lupus nephritis.