OVA/SEB allergic peritonitis is a MC dependent model.
Since one of our main aims was to establish a MC dependent model, we examined, 30 min post challenge in the OVA/SEB AP, tryptase and TNFα levels in the peritoneal lavage as markers of MCs degranulation. Both these preformed mediators were found to be significantly increased in the OVA/SEB-challenged mice in comparison to PBS-challenged ones (Fig. 4A-B). Likewise, vascular permeability in the peritoneum was significantly increased at the 30 min time point, further bolstering the MC role in this model (Fig. 4C).
Moreover, we induced the OVA/SEB AP model in MC deficient Sash mice. Forty-eight hours post challenge total cell infiltration into the peritoneal cavity was increased both in AP induced Sash mice and WT mice, although Sash mice presented slightly lower cell infiltration than WT ones (1.4- and 1.8-fold increase, respectively) (Fig. 5A). However, Eos numbers in the peritoneal cavity were significantly reduced in Sash OVA/SEB challenged mice in comparison to the WT group (Fig 5A). sCD48 levels in the peritoneal cavity were significantly augmented in the WT OVA/SEB group but not significantly in the Sash OVA/SEB group (Fig. 5B). Noteworthy, macrophages numbers showed a small albeit not significant increase in OVA/SEB challenged WT mice but no difference in the corresponding group of Sash mice (Fig. 5A). It is important to mention that in the OVA/SEB Sash mice group, two mice were found to have MCs in the peritoneal cavity and developed inflammation as WT mice. Therefore, they were excluded from the experiment (data not shown). To further dissect the role of MCs in our peritonitis model, Sash mice were reconstituted with BMMCs in the peritoneum in an “overshoot fashion” (2X106 cells) 24 hours before challenge (S3). Forty-eight hours post challenge, when MC numbers were found to be ~106 (Fig. 6A), inflammation was partially restored, as demonstrated by increments in total cell and in Eos numbers in comparison to non-reconstituted Sash mice (Fig 6A-B).