P1612: CALPROTECTIN LEVELS ARE ELEVATED IN CONGENITAL TTP AND IMMUNE TTP AT ADAMTS13 RELAPSE
摘要
Topic: 32. Platelet disorders Background: Calprotectin (also known as S100A8/A9) is a proinflammatory protein that is secreted by neutrophils. A previous study by Sui et al (2020) demonstrated calprotectin was elevated during acute immune TTP episodes, with higher levels associated with mortality; and postulated that it may also be involved in the pathogenesis of TTP by playing a role in thrombus formation. Aims: We sought to examine whether calprotectin levels were elevated in TTP patients in different clinical scenarios to determine if it could be used to predict relapse or was simply a marker of inflammation during acute episodes. Methods: A retrospective study was carried out in patients consented to the UK TTP registry where frozen, citrated plasma was thawed and levels were measured using a human S100A8/A9 DuoSet ELISA kit (R&D Systems, Minneapolis, MN), according to the manufacturer’s instructions. In total, 95 TTP patient episodes were tested, of which 40 were patients that had an ADAMTS13 relapse, 30 were congenital patients and 5 were immune TTPs in complete remission. The remaining episodes were acute: 12 immune TTP and 8 congenital TTP. The mean age of patients at the time of an episode was 42 years (range 0 – 83 years). 40 normal control citrated plasma samples were also tested. Results: In clinical remission, the median calprotectin level for ADAMTS13 relapse episodes was 0.76 µg/ml (range 0.02 – 2.31), which was similar to congenital patients at 0.72 µg/ml (0.03 – 14.45) but significantly higher than normal controls: 0.33 µg/ml (0.06 – 0.91). Interestingly, although only 5 TTP patients in complete remission were tested, their calprotectin level was also raised compared to normal controls at 0.6 µg/ml (0.33 – 1.22). Levels were considerably higher in acute episodes with 15.3 µg/ml (4.9 – 242) in congenital patients and 64.3 µg/ml (0.99-332) in immune TTP patients. Summary/Conclusion: Calprotectin is markedly elevated during both acute immune and congen