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To evaluate the effect of prednisolone on NK cell cytotoxicity in vitro environment and also to compare the effect of prednisolone versus immunoglobulin-G (IVIG) on NK cell cytotoxicity using in vitro co-culture with K562 cells.The following is a prospective observational study, between August 2006 and February 2007, was carried out on blood samples from 110 patients with a history of recurrent miscarriage or recurrent failed implantation. Peripheral blood mononuclear cells containing NK cells were isolated and co-cultured with target cell K562 in three different effector-to-target (E:T) ratios of 50:1, 25:1 and 12.5:1. Prednisolone or IVIG was then added to the tube with E:T ratio of 50:1 to assess suppressive effect. The percentage killing was recorded and statistical analysis performed using Student's t-test.In the experiments with an E:T ratio of 50:1 without prednisolone or IVIG in the co-culture, the mean target cell killing percentage was 26.4%. In cultures using the same E:T ratio, this killing percentage was significantly reduced in the presence of IVIG (9.9%) or prednisolone (13.6%), (P0.001 in both analyses). On comparing the reduction in killing percentage of target cells by prednisolone versus IVIG, a slightly lower reduction in the prednisolone co-culture was noted but this was not statistically significant (P0.05).The results of this study show that prednisolone is able to suppress the cytolytic activity of the NK cell. Prednisolone and IVIG are almost equally effective in suppressing in vitro NK cell cytolytic activity.

To evaluate the association of serum tumour necrotic factor (TNF)-alpha and interferon (IFN)-gamma levels with IVF treatment outcome and peripheral blood NK cells.Prospective observational study of 126 randomly selected women who underwent IVF treatment. The serum levels of TNF-alpha and IFN-gamma were determined by multiplex suspension beads array system.There were no significant differences with regard to the systemic TNF-alpha and IFN-gamma levels between the pregnant (n = 51, TNF-alpha: 53.5 pg/mL; IFN-gamma: 4.6 pg/mL) and not pregnant (n = 75, TNF-alpha: 63.0; IFN-gamma: 7.5) women after IVF treatment. For those women with a positive pregnancy after IVF treatment, the systemic TNF-alpha and IFN-gamma levels were higher in those women who miscarried (n = 13, TNF-alpha: 67.4; IFN-gamma: 9.1) when compared with those who had a live birth (n = 38, TNF-alpha: 48.7; IFN-gamma: 1.4), however this difference was not statistically significant. Interestingly, the systemic TNF-alpha and IFN-gamma levels were significantly higher in women who had a higher level of activated (CD69(+)) NK cells (n = 39, TNF-alpha: 86.8; IFN-gamma: 4.7) when compared with women who had a low level of activated NK cells (n = 87, TNF-alpha: 46.9; IFN-gamma: 1.7 P = 0.028 and 0.045 respectively).The systemic levels of TNF-alpha and IFN-gamma have no association with implantation rate or miscarriage rate in women undergoing IVF treatment. However, high levels of TNF-alpha and IFN-gamma are associated with elevated levels of activated NK cells and this may subsequently exert a negative impact on reproduction.