Figure 1. Meprin β is important for immune cell extravasation during acute inflammation.

(A) CD99 is crucial for TEM. Extravasation of leukocytes through endothelial layers requires specific interactions of adhesion molecules between both cell types. Chemokines and other biologically active factors secreted by mesenchymal cells induce leukocyte migration. Whether or not CD99 also plays a role in tumor cell extravasation during metastasis is unknown because these mechanisms are much more heterogeneous. (B) For an acute inflammation model, Mep1b^+/+ and Mep1b^–/– mice were injected subcutaneously with sterile air. Six days later carrageenan was administered into the dorsal air pouch to induce an immune cell infiltration. After 24 h, the pouch was washed and the lavage fluid collected for further analysis. (C) Cells in the pouch lavage fluid were counted. Mep1b^–/– mice had significantly less infiltrated cells than Mep1b^+/+ mice.