Effect of serum interleukin-21 on B cell secretory capacity and apoptosis in patients with systemic lupus erythematosus / 中华内科杂志

ABSTRACT

Objective To investigate the secretory capacity and apoptosis of interleukin ( IL)-21 induced normal B cells by co-culture with serum from patients with systemic lupus erythematosus (SLE). Methods Serum from twenty new-onset SLE patients and 20 healthy donors were collected .CD1+9 B cells from the normal controls were co-cultured with serum from SLE patients in the presence or absence of IL-21-R-FC(4 μg/ml).Supernatant IgG and IgM concentration were measured by immunoturbidimetric assay on day 5.Supernatant anti-dsDNA level was determined by ELISA .The percentage of apoptotic cells was detected by flow cytometer.Results IgG,IgM and anti-dsDNA levels in normal B cells with SLE serum were significantly higher than those in the serum of SLE patients alone [ ( 5.84 ±1.79 ) g/L vs ( 4.25 ± 1.48)g/L,P=0.000;(0.46 ±0.21)g/L vs (0.43 ±0.21)g/L,P=0.003;(127.76 ±70.24)IU/ml vs (115.15 ±63.88) IU/ml,P=0.014 respectively].However, no significant differences were found in the group of normal B cells with non-homologous serum from normal controls (P>0.05).Supernatant IgG, IgM and anti-dsDNA levels in normal B cells with SLE serum significantly decreased while IL-21R-fusion protein was added [(5.26 ±1.62)g/L vs (5.84 ±1.79)g/L, P=0.006;(0.42 ±0.20)g/L vs (0.46 ±0.21)g/L, P=0.002;( 118.00 ±69.62 ) IU/ml vs ( 127.76 ±70.24 ) IU/ml, P =0.012 respectively ] .The apoptotic rate of B cells with SLE serum was significantly higher than that with normal serum [ ( 47.88 ± 12.65)%vs (38.86 ±10.32)%,P =0.004].But adding IL-21R-fusion conversed the apoptotic rates [(42.08 ±12.52)%vs (47.88 ±12.65)%,P=0.001].Conclusions SLE serum could induce normal B cells to form immunoglobulin secreting cells and producing autoantibodies , or apoptosis in pathological conditions.IL-21 might be considered as a potential therapeutic target of SLE .