It has been demonstrated that patients with asthma have a large number of NK cells and show a stronger NK activity. These results indicate that NK cell activity may be related to total IgE level in serum in healthy subjects. Previously

we have found that sodium butyrate （NaBu） markedly enhanced the IL- 4- induced IgE production in the LPS- stimulated murine splenocytes in vitro

and inductive rat IgE production in vivo

and enhanced the NK cell activity ex vivo .We hypothesized that the IgE production might be involved in butyrate- enhanced NK cell activity in vivo. Mice were intraperitoneally treated/immunized with NaBu or/and Ascaris suum extract （ASC）

and the spleen NK cell activity was evaluated. Furthermore

the effect of serum （NAS） on IL- 2- or IFN-γ- induced spleen NK cell activity was determined. The spleen NK cell activity and IL- 2- or IFN-γ- induced spleen NK cell activity of mice treated/immunized with NaBu or/and ASC were stronger than those of untreated/unimmunized mice. Although IL- 4 blocked IL- 2 （100 U/ml）- or IFN-γ （100 U/ml）- induced increase in NK cell activity

these NK cell activities in mice treated/immunized with NaBu/ASC were not inhibited. IgE production showed a tendency to rise in NaBu- treated mice serum

and a synergistic effect was observed with treatment of NaBu and ASC. Moreover

the NAS significantly increased IL- 2（25 U/ml）- or IFN-γ （25 U/ml）- induced NK cell activity

and its effect was inhibited by anti- mouse IgE mAb. These data show that IgE plays an important role in NAS- enhanced IL- 2/IFN-γ- induced NK cell activity

and IL- 4 does not inhibit IgE and IL- 2/IFN-γ- induced NK cell activity in mice.