Abstract
Poncirus trifoliata (L.) Raf (Rutaceae) fruits (PTFE) has been used for the treatment of allergic disease. IgE is normally one of the least abundant immunoglobulin (Ig) isotypes in the serum of both humans and several species of experimental animals: however a number of different stimuli can result in profound increases in IgE levels relative to other isotypes. In rodents, infection with many parasitic helminths can cause approximately 100-fold elevation in IgE within 2 wks. Immunization of mice with small amounts of protein antigens on alum also results in 10-fold to fold increase in total serum IgE, much of it specific for the immunizing antigen. In this experiment, I investigated the effect of an aqueous extract of Poncirus trifoliata (L.) Raf (Rutaceae) fruits (PTFE) on a in vivo and in vitro IgE production. PTFE dose-dependently inhibited the serum levels of IgE induced by antigens. The regulation of IgE synthesis is influenced by T cells and T cell derived factors. IL -4, a T cell-derived cytokine, has been shown to stimulate murine IgE synthesis both in vitro and in vivo. Current evidence suggests that IL-4 induces IgE synthesis in the mouse by stimulating H chain isotype switch. Lipopolysaccharide (LPS) plus IL-4 cause about l00-fold increase in IgE secretion by murine B cells. The effects of PTFE on the IL-4-dependent IgE response by mouse whole spleen cells were studied. Whole spleen cells were cultured for 7 days in the presence of LPS plus IL-4 and PTFE and the supernatants were assayed for IgE. IL-4 dependent IgE production of LPS-stimulated whole spleen cells was inhibited by PTFE. Moreover, in the present study using U266Bl human IgE-bearing B cells, I found that PTFE inhibited the production of IgE activated by LPS plus IL-4. These results indicate that PTFE have antiallergic activity by inhibition of IgE production from B cells.