Role of blood ribosomal protein S19 in coagulum resorption: A study using Gln137Glu‐ribosomal protein S19 gene knock‐in mouse

Sera of human, guinea pig or mouse contain a strong monocyte chemoattractant capacity that is attributed to the ribosomal protein S19 (RP S19) oligomers generated during blood coagulation. In contrast, sera prepared from Gln137Glu‐RP S19 gene knock‐in mice contained negligible chemoattractant capacity. When coagula that had been pre‐formed from the blood of both the wild type and knock‐in mice were intraperitoneally inserted into host mice, after 3 days of recovery, the knock‐in mouse coagula remained larger than the wild type mouse coagula. The wild type mouse coagula were covered by multiple macrophage layers at the surface and were infiltrated inside by macrophages. Knock‐in mouse coagula exhibited less macrophage involvement. When coagula of knock‐in mice and coagula of knock‐in mice containing C5a/RP S19, an artificial substitute of the RP S19 oligomers, were intraperitoneally inserted as pairs, the C5a/RP S19 containing coagulum was more rapidly absorbed, concomitant with increased macrophage involvement. Finally, when the knock‐in mouse and wild type mouse coagula pairs were inserted into mice in which macrophages had been depleted using clodronate liposome, the size difference of recovered coagula was reversed. These results indicate the importance of the RP S19 oligomer‐induced macrophage recruitment in coagulum resorption.