title: Crocodylus siamensis serum and macrophage phagocytic activity.
abstract: Antimicrobial activity of sera from many crocodilian species has been recognized. This activity was proposed to be mediated, at least in part, by complement. Due to the fact that complement proteins have different functions in the immune system, they may be involved in phagocytic process of phagocytes. In the present study, the effects of Siamese crocodile serum on phagocytic activity of macrophages as well as the possible involvement of complement in this process were examined. The results showed increases in the phagocytosis of both Escherichia coli and to a lesser extent, Staphylococcus aureus upon incubation of murine macrophage cell line with fresh crocodile serum (FS). Similar to FS, other crocodile blood products, including freeze dried serum (DS) and freeze dried whole blood (DWB) exhibited phagocytosis-enhancing property. However the ability of DWB to enhance phagocytosis was less efficient than that of FS and DS, suggesting that serum factors were involved in this process. Treatment of FS with heat at 56 degrees C for 30 min deteriorated the effect of FS on bacterial uptake of macrophages, suggesting that complement proteins play a role in the modulation of the phagocytic process. Collectively, the results of the present study suggested that crocodile serum enhances the macrophage phagocytic activity through complement activity and, therefore, may be taken as an alternative medicine for supporting the human immune responses.
authors.affiliation: Department of Preclinical Science, Faculty of Medicine, Thammasat University, Rangsit Campus, Pathumthani, Thailand. kalaya@tu.ac.th
authors.forename: Kalaya
authors.initials: K
authors.lastname: Aree
authors.forename: Jindawan
authors.initials: J
authors.lastname: Siruntawineti
authors.forename: Win
authors.initials: W
authors.lastname: Chaeychomsri
mesh_terms: D000489:Alligators and Crocodiles; D000818:Animals; D001770:Blood Bactericidal Activity; D018929:Cell Culture Techniques; D003165:Complement System Proteins / Q000502:physiology; D004926:Escherichia coli; D006801:Humans; D008264:Macrophages / Q000502:physiology*; D010587:Phagocytosis / Q000502:physiology*; D013211:Staphylococcus aureus; D013785:Thailand
chemical_list: D003165:Complement System Proteins