FUT4 and leptospirosis: Thus, the decrease of CD15 level in leptospirosis cases might reflect a poor capacity of circulating PMN to be recruited to the tissues infected by Leptospira. CD11b (alpha subunit of CR3) is crucial for the slow rolling, adherence and transendothelial migration towards inflamed tissues as well as phagocytosis of complement opsonized-bacteria [15].