Expression of uPAR by hematopoietic cells promotes susceptibility to CIA. (A-D) Bone marrow from either uPAR WT or Plaur^−/− mice was transplanted into WT recipients. (A) The percentage of mice free from macroscopic arthritis in the paws is shown for the 3-week evaluation period following the second CII immunization. Note that ∼60% of Plaur^−/− transplanted mice remained arthritis-free based on visible inspection through the CIA study period (P < .05, Kaplan-Meier log-rank analysis). (B-C) The median arthritis index revealed a significant diminution in number of arthritic joints with transplant of Plaur^−/− bone marrow cells (B), with individual scores indicated for day 42 (C). The median arthritis severity for the same cohort of mice revealed a reduction in paw swelling for CIA-challenged mice with transplant of Plaur^−/− bone marrow cells (D). (E-H) Bone marrow from WT or Plaur^−/− mice was transplanted into Plaur^−/− recipients. (E) The percentage of mice free from macroscopic arthritis in the paws is shown for the 3-week evaluation period following the second CII immunization, with ∼65% of Plaur^−/− bone marrow recipients remaining arthritis-free. (F-G) The median arthritis index revealed a significant diminution in number of arthritic joints with transplant of Plaur^−/− bone marrow cells (F), with individual scores indicated for day 42 (G). The median arthritis severity for the same cohort of mice revealed a reduction in paw swelling for CIA-challenged mice with transplant of uPAR^−/− bone marrow cells (H). For WT recipient experiments, n = 11 uPAR WT mice and n = 12 Plaur^−/− mice. For uPAR-deficient recipients, n = 11 uPAR WT mice and n = 12 Plaur^−/− Mice. P values were determined by Mann-Whitney U test.