Long-term high molecular weight kininogen (HK) deficiency prolongs survival and reduces inflammation in sickle mice. Two-month-old wild type (WT) and HK−/− mice were lethally irradiated and transplanted with bone marrow from AA and SS mice. A, Kaplan-Meier survival curve of SS/WT (gray, n = 27 at day 0) and SS/HK−/− (blue, n = 21 at day 0) mice after bone marrow transplantation, and analyzed by Mantel-Cox test, with a significant difference in survival of **P < .01. After 8 months, blood and was collected for analysis of (B) neutrophil-lymphocyte ratio. *P < .05 and **P < .01 versus AA/WT; asterisks above lines indicate difference from SS/WT