Toll-like receptor 4 surface expression on human monocytes and B cells is modulated by IL-2 and IL-4

Human Toll-like receptor 4 (TLR4) has recently been identified. and it has been shogun to be the main protein involved in recognizing gram-negative bacteria. We examined the regulation of TLR4 surface expression in human peripheral blood monocytes and B cells by interleukin-2 (IL-2) and IL-4. IL-2 up-regulated TLR4 surface expression on human peripheral blood monocytes. but did not change expression on human peripheral B cells. By contrast, IL-4 don-regulated TLR4 surface expression on human peripheral blood monocytes. but up-regulated TLR4 surface expression on human peripheral B cells. These results indicate that Th1 cytokine IL-2 enhances receptors involved in the response to gram-negative bacteria and that activation of cellular immunity may enhance defense against these pathogens through monocytes, but not B cells, whereas Th-2 cytokine IL-4 modulates the receptor response to gram-negative bacteria and that activation of humoral immunity may enhance defense against these pathogens through B cells, but not monocytes. (C) 2002 Elsevier Science B.V. All rights reserved.