Effect of deletion of the candidate fibrin receptors αMβ2, ICAM-1, the principal myeloid integrin engagement site on fibrin, and the mannose receptor on endocytic fibrin uptake. (A-L) Expression of candidate fibrin-internalization receptors by CCR2-positive, fibrin-internalizing cells. (A,E,I) Representative examples of flow cytometry analysis of CD45-positive, CCR2-positive, fibrin-internalizing cells from fibrin-internalization zones stained with antibodies against CD11b (A), ICAM1 (E), and MR (I). (B,F,J) Representative examples of flow cytometry analysis of CD45-positive spleen cells stained with antibodies against CD11b (B), ICAM1 (F), and MR (J) as positive control. (C,G,K) Flow cytometry analysis of CD45-positive spleen cells with primary antibody omitted (negative control). Diagrams show intensity of staining vs forward scatter. Boxes show gate for positive signal with percentage of cell in gate indicated. (D,H,L) CD45-positive, CCR2-positive, fibrin-internalizing cells from fibrin internalization zones expressing CD11b (D, N = 3 mice), ICAM1 (H, N = 3 mice), and MR (L, N = 3 mice). Data are shown as mean with standard deviation. (M) Enumeration of cell accumulation in implantation zones from wild-type mice (left bars, N = 7 mice) and αMβ2-deficient Itgam^−/− littermates (right bars, N = 6 mice). (N) Enumeration of cell accumulation in implantation zones from wild-type mice implanted with fibrin derived from wild-type mice (left bars, N = 5 mice) or with fibrin derived from Fgg^390-396A littermates (right bars, N = 5 mice). (O) Enumeration of cell accumulation in implantation zones from wild-type mice (left bars, N = 4 mice) and ICAM1-deficient Icam^−/− littermates (right bars, N = 4 mice). (P) Enumeration of cell accumulation in implantation zones from wild-type mice (left bars, N = 3 mice) and MR-deficient Mrc1^−/− littermates (right bars, N = 3 mice). Data in panels M-P are shown as mean values and standard deviations. Significance was determined by Student t test (2 tailed). (Q) Enumeration of the fibrin-endocytosing fraction of cells in implantation zones from wild-type mice (left triangles) and αMβ2-deficient Itgam^−/− littermates (right triangles). (R) Enumeration of the fibrin-endocytosing fraction of cells in implantation zones from wild-type mice implanted with fibrin derived from wild-type mice (left triangles) or with fibrin derived from Fgg^390-396A littermates (right triangles). (S) Enumeration of the fibrin-endocytosing fraction of cells in implantation zones from wild-type mice (left triangles) and ICAM1-deficient Icam^−/− littermates (right triangles). (T) Enumeration of the fibrin-endocytosing fraction of cells in implantation zones from wild-type mice (left triangles) and MR-deficient Mrc1^−/− littermates (right triangles). Data in panels Q-T are shown as individual values for each mouse, as well as mean values and standard deviations. Significance was determined by Student t test (2 tailed).