Abstract
We have previously reported a mitogenic effect of a tea catechin, epigallocatechin gallate, on B cells. In the present study, we found that tea catechin enhances plaque-forming cell responses to sheep red blood cells in mice in vitro and in vivo. Tea catechin showed a mitogenic effect on spleen cells of nude mice. Removal of macrophages from spleen cells did not diminish the mitogenic activity of tea catechin. Therefore, tea catechin may directly promote the proliferation and differentiation of B cells. Preliminary experiments show that, as with lipopolysaccharide, signal transduction through tyrosine kinase may play a role in the enhancement by tea catechin, since a tyrosine kinase inhibitor, genistein, inhibited the mitogenic effect of epigallocatechin gallate while inhibi-tors of protein kinase A and C failed to do so. The above results suggest that tea catechin enhances immune functions both in vitro and in vivo.
