The effect of mineral trioxide aggregate on phagocytic activity and production of reactive oxygen, nitrogen species and arginase activity by M1 and M2 macrophages T. M. B. Rezende 1 , L. Q. Vieira 2 , F. P. Cardoso 1 , R. R. Oliveira 1 , S. T. de Oliveira Mendes 1 , M. L. R. Jorge 1 & A. P. Ribeiro Sobrinho 1 1 Departamento de Dentı ´stica Restauradora, Faculdade de Odontologia, Universidade Federal de Minas Gerais, Belo Horizonte; and 2 Departamento de Bioquı ´mica e Imunologia, Instituto de Cie ˆncias Biolo ´gicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil Abstract Rezende TMB, Vieira LQ, Cardoso FP, Oliveira RR, de Oliveira Mendes ST, Jorge MLR, Ribeiro Sobrinho AP. The effect of mineral trioxide aggregate on phagocytic activity and production of reactive oxygen, nitrogen species and arginase activity by M1 and M2 macrophages. International Endodontic Journal, 40, 603–611, 2007. Aim To assess the influence of co-culture with min- eral trioxide aggregate (MTA) on phagocytosis and the production of reactive oxygen intermediates (ROI) and nitrogen (NO) species and the arginase activity by M1 and M2 peritoneal macrophages. Methodology Cellular viability, adherence and pha- gocytosis of Saccharomyces boulardii were assayed in the presence of MTA. Macrophages were stimulated with zymosan for ROI assays and with Fusobacterium nucle- atum and Peptostreptococcus anaerobius and IFN-c for NO production and arginase activity, when in contact with capillaries containing MTA. Data were analysed by T, anova, Kruskall–Wallis and Mann–Whitney tests. Results M2 macrophages displayed greater cellular viability in polypropylene tubes, greater ability to ingest yeast and smaller production of ROI and higher arginase activity when compared with M1 macroph- ages. Both macrophages, M1 and M2, presented similar cell adherence and NO production. The addition of bacterial preparations to macrophages interfered with NO and arginase productions. MTA did not interfere with any of the parameters measured. Conclusions Phagocytosis and the ability of the two macrophage subtypes to eliminate microbes were not affected by MTA. Keywords: macrophage, mineral trioxide aggregate, phagocytosis, reactive nitrogen species and arginase activity, reactive oxygen species. Received 15 August 2006; accepted 12 January 2007 Introduction Mineral trioxide aggregate (MTA) consists of hydrophi- lic tri-calcium silicate particles, tri-calcium aluminates, tri-calcium oxide, silicate oxide and other mineral oxides (Lee et al. 1993b, Torabinejad et al. 1993, Abedi & Ingle 1995, Torabinejad & Chivian 1999). MTA is sold under the brand name ProRoot Ò (Dentsply Maillefer, Ballaigues, Switzerland) and, in Brazil, MTA- Angelus Ò (Odonto-lo ´gika, Londrina, Brazil). As MTA is indicated for the use in inflamed or infected areas, it ought to be biocompatible and not affect cell behaviour. Macrophages predominate amongst the several cells present in the inflamed pulp and periapical tissues (Stern et al. 1981, Kawashima et al. 1996). Recently, macrophages have been divided into two subtypes: M1 and M2, according to their ability to produce different types of responses (Mills et al. 2000, Bastos et al. 2002, Correspondence: Dr Anto ˆnio Paulino Ribeiro Sobrinho, Departamento de Odontologia Restauradora, Faculdade de Odontologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil (Tel.: 55-31-34992460; fax: 55-31- 34992472; e-mail: sobrinho.bhz@terra.com.br). doi:10.1111/j.1365-2591.2007.01255.x ª 2007 International Endodontic Journal International Endodontic Journal, 40, 603–611, 2007 603