ERYTHROCYTE-DEPENDENT MITOGENIC ACTIVITY OF EPIGALLOCATECHIN GALLATE ON MOUSE SPLENIC B-CELLS

We previously reported that epigallocatechin gallate (EGCg), the main constituent of tea catechins, displays mitogenic effect on mouse splen ic B cells. During research into the mechanism(s), it was found that t he mitogenic activity of EGCg was dependent on the presence of red blo od cells (RBC). When RBC in T cell-depleted spleen cells were removed, EGCg did not enhance the proliferation of B cells and even showed tox ic effect at 25-50 mu g/ml. When mouse, rabbit or sheep RBC as well as RBC-ghosts were added into the cultures, EGCg showed the mitogenic ac tivity at a range of 1-50 mu g/ml. Thereafter, we preincubated RBC wit h EGCg at 4 degrees C for various times and then washed the RBC to rem ove free EGCg in the suspensions. The EGCg-preincubated RBC also enhan ced B cell proliferation. As short as ten minutes was sufficient for E GCg to bind to RBC membrane. These results indicate that EGCg first at tached to the membrane of RBC and then stimulated B cell proliferation . The above results suggest an important immunoregulatory function of RBC. (C) 1998 International Society for Immunopharmacology.