A 63-year-old man becomes febrile and begins expectorating large amounts of mucopurulent sputum. Sputum cultures are positive for Gram-positive diplococci. Which of the following mediators of inflammation provides potent chemotactic factors for the directed migration of inflammatory cells into the alveolar air spaces of this patient?

Chemotactic factors are substance that stimulalte cellular migration The most potent chemotactic factors for leukocytes at the site of injury are:- Complement proteins (e.g., C5a) Bacterial and mitochondrial products, paicularly low molecular weight N-formylated peptides Products of arachidonic acid metabolism (especially LTB4) -Plasmin is a fibrinolytic enzyme generated by activated Hageman factor (clotting factor XII).