Cre/lox Studies Identify Resident Macrophages as the Major Source of Circulating Coagulation Factor XIII-A.

Objective: To establish the cellular source of plasma factor (F)XIII-A.

Approach And Results: A novel mouse floxed for the gene, FXIII-A (Flox), was crossed with myeloid- and platelet-cre-expressing mice, and cellular FXIII-A mRNA expression and plasma and platelet FXIII-A levels were measured. The platelet factor 4-cre.