[Effects of simulated weightlessness on biological activity of human NK cells induced by IL-2].

OBJECTIVE: To investigate the effects of simulated weightlessness on the activity of human natural killer (NK) cells induced by interleukin 2 (IL-2). METHODS: Primary human NK cells were cultured under simulated weightlessness condition. The viability of NK cells was determined by CCK-8 assay; cell apoptosis was analyzed by flow cytometry combined with annexin V-FITC/PI staining; the level of interferon γ (IFN-γ) was examined by ELISA; the mRNA levels of IL-12 receptor genes were detected by reverse transcription PCR. RESULTS: Compared with control cells cultured in normal gravity, IL-2-induced cell proliferation rate of NK cells cultured in simulated weightlessness decreased by 13.6% and 31% at 24 and 48 hours, respectively; the cell apoptotic rate increased by 8% and 19%; IL-2-induced IFN-γ production was inhibited by 25.2% and 47.8%; the cytotoxicity of NK cells induced by IL-2 was reduced by 7% and 18%; IL-12-induced IFN-γ production was suppressed by 21.8% and 58.8% in IL-2 pretreated cells at 24 and 48 hours, respectively. In addition, the mRNA levels of IL-12 ß1 and ß2 receptor genes were significantly down-regulated in the cells cultured in simulated weightlessness. CONCLUSION: Simulated weightlessness can inhibit the proliferation of NK cells induced by IL-2, promote NK cell apoptosis, impair IL-2-induced IFN-γ production and cytotoxicity in NK cells, and inhibit IL-12-induced IFN-γ production through down-regulating IL-12 receptor gene expression in NK cells.

Immunological evaluation of SW-HSA conjugate on goats.

Locoweeds cause significant livestock poisoning and economic loss all over the world. The purpose of this study was to investigate the immune effects of locoweed toxin, swainsonine (SW) and human serum albumin (HSA) conjugate (SW-HSA), on goats. Twenty-four Sannon goats were randomly separated into immune control group (eight goats), immune poisoning group I (six goats), immune poisoning group II (six goats) and poisoning control group (four goats). Immune control group, immune poisoning groups I and II were first vaccinated with SW-HSA conjugate. The poisoning control group, immune poisoning groups I and II were then fed with 10.0 g/kg BW/day dry powder of Oxytropis kansuensis Bunge everyday morning. The immune control group was supplied with an alfalfa-based diet. Blood samples of these experimental animals were collected at different time interval. Immunoassay was performed using indirect ELISA and E-rosette technique. The results show that, after second booster immunization: (1) anti-SW antibody level in some goats increased to 2(8), which proves that SW-HSA conjugate can induce experimental animals to produce high-level anti-SW antibody in their bodies; (2) the high-level antibody in their bodies could maintain 30 days, and decreased gradually after poisoning experiment (in our experiment, there was a return of the antibody level on day 21 after poisoning experiment); (3) the decreasing of the E-rosette rate of the immune poisoning group was delayed 14 days, which suggests that SW-HSA could low down the loss of the immunity of the goats; (4) swainsonine concentration in the blood was significantly lower (p<0.01) in the immune poisoning groups than that in the poisoning control group, and there was no significant difference (p>0.01) between the two immune poisoning groups within the poisoning experiment.