Stimulation of TCR V gamma 3 cells by gram-negative bacteria

A distinct feature of most murine TCR-gamma delta cells is that they localize in epithelial tissues that cover the internal and external surface of the body. Therefore, TCR-gamma delta cells have been hypothesized to represent a first line of defense against invading pathogens. In this study, it is shown that TCR V gamma 3 cells are activated to produce cytokines upon interaction with Gram-negative bacteria, whereas Gram-positive bacteria have no effect. Accessory cells are not required. LPS of Gram-negative bacteria is shown to be the stimulating structure for TCR V gamma 3 cells, as the stimulation is inhibited by addition of polymyxin B or anti-LPS Ab and as purified LPS stimulates V gamma 3 T cells. Blocking of the V gamma 3 TCR does not inhibit stimulation by Gram-negative bacteria, whereas suboptimal triggering of the TCR is synergistic. These results demonstrate that LPS is an important stimulus for TCR V gamma 3 cells. This indicates that skin-located V gamma 3 T cells might play a role in the defense against Gram-negative bacteria.