Effect of Anatomical Distribution of Mast Cells on Their Defense Function against Bacterial Infections : Demonstration Using Partially Mast Cell–deficient tg/tg Mice

Mast cells were depleted in the peritoneal cavity of WBB6F₁-tg/tg mice that did not express a transcription factor, MITF. When acute bacterial peritonitis was induced in WBB6F₁-+/+, WBB6F₁-W/W^v, and WBB6F₁-tg/tg mice, the proportion of surviving WBB6F₁-+/+ mice was significantly higher than that of surviving WBB6F₁-W/W^v or WBB6F₁-tg/tg mice. The poor survival of WBB6F₁-W/W^v and WBB6F₁-tg/tg mice was attributed to the deficient influx of neutrophils into the peritoneal cavity. The injection of cultured mast cells (CMCs) derived from WBB6F₁-+/+ mice normalized the neutrophil influx and reduced survival rate in WBB6F₁-W/W^v mice, but not in WBB6F₁-tg/tg mice. This was not attributable to a defect of neutrophils because injection of TNF-α increased the neutrophil influx and survival rate in both WBB6F₁-W/W^v and WBB6F₁-tg/tg mice. Although WBB6F₁-+/+ CMCs injection normalized the number of mast cells in both the peritoneal cavity and mesentery of WBB6F₁-W/W^v mice, it normalized the number of mast cells only in the peritoneal cavity of WBB6F₁-tg/tg mice. Mast cells within the mesentery or mast cells in the vicinity of blood vessels appeared to play an important role against the acute bacterial peritonitis. WBB6F₁-tg/tg mice may be useful for studying the effect of anatomical distribution of mast cells on their antiseptic function.