Background: Many cases of autoimmune hemolytic anemia have been reported after viral infection. Phagocyte activation and accompanying erythrophagocytosis are thought to result from proinflammatory cytokines released during viral infection. SIRP-α (signal regulatory protein-α), a receptor expressed on phagocytes, inhibits phagocytosis when bound to CD47 on the erythrocyte membrane. Ligation with CD47 results in SHP-1 recruitment to SIRP-α and dephosphorylation of specific downstream substrates involved in phagocytosis. SIRP-α ligation by CD47 may be inhibited by proinflammatory cytokines. Objectives: The aim of this work was to evaluate the effect of IFN-β, IFN-γ, and TNF-α on erythrophagocytosis and assess the effect on expression of SIRP-α and SHP-1 in human monocytes. Materials and methods: Monocytes were cultured ex vivo with IFN-β or IFN-γ/TNF-α. Erythrophagocytosis was determined by flow cytometry. SIRP-α and SHP-1 gene expression was determined by real time-PCR, while SIRP-α and SHP-1 protein expression was determined by western blot. Results: Erythrophagocytosis by monocytes significantly decreased after treatment with either IFN-β or IFN-γ/TNF-α. Monocytes cultured with IFN-γ/TNF-α showed increased SIRP-α gene and protein expression and SHP-1 gene expression. Monocytes cultured with IFN-β did not show any alteration in SIRP-α or SHP-1 expression. Conclusion: We conclude that IFN-β and IFN-γ/TNF-α decrease erythrophagocytosis by human monocytes in vitro, and this effect does not apparently require an increase in SIRP-α or SHP-1 expression. © 2012 Informa Healthcare USA, Inc.34610541059Javierre, B.M., Hernando, H., Ballestar, E., Environmental triggers and epigenetic deregulation in autoimmune disease (2011) Discov Med, 12, pp. 535-545Delogu, L.G., Deidda, S., Delitala, G., Manetti, R., Infectious diseases and autoimmunity (2011) J Infect Dev Ctries, 5, pp. 679-687Fujinami, R.S., Von Herrath, M.G., Christen, U., Whitton, J.L., Molecular mimicry, bystander activation, or viral persistence: infections and autoimmune disease (2006) Clin Microbiol Rev, 19, pp. 80-94McCoy, L., Tsunoda, I., Fujinami, R.S., Multiple sclerosis and virus induced immune responses: autoimmunity can be primed by molecular mimicry and augmented by bystander activation (2006) Autoimmunity, 39, pp. 9-19Musaji, A., Meite, M., Detalle, L., Franquin, S., Cormont, F., Prt, V., Izui, S., Coutelier, J.P., Enhancement of autoantibody pathogenicity by viral infections in mouse models of anemia and thrombocytopenia (2005) Autoimmun Rev, 4, pp. 247-252Meite, M., Lnard, S., Idrissi, M.E., Izui, S., Masson, P.L., Coutelier, J.P., Exacerbation of autoantibody-mediated hemolytic anemia by viral infection (2000) J Virol, 74, pp. 6045-6049Von Herrath, M.G., Oldstone, M.B., Virus-induced autoimmune disease (1996) Curr Opin Immunol, 8, pp. 878-885Ramshaw, I.A., Ramsay, A.J., Karupiah, G., Rolph, M.S., Mahalingam, S., Ruby, J.C., Cytokines and immunity to viral infections (1997) Immunol Rev, 159, pp. 119-135Condino-Neto, A., Whitney, C., Newburger, P.E., Dexamethasone but not indomethacin inhibits human phagocyte nicotinamide adenine dinucleotide phosphate oxidase activity by downregulating expression of genes encoding oxidase components (1998) J Immunol, 161, pp. 4960-4967Ray, J.C., Wang, J., Chan, J., Kirschner, D.E., The timing of TNF and IFN-gamma signaling affects macrophage activation strategies during Mycobacterium tuberculosis infection (2008) J Theor Biol, 252, pp. 24-38Tomioka, H., Sato, K., Maw, W.W., Saito, H., The role of tumor necrosis factor, interferon-gamma, transforming growth factorbeta, and nitric oxide in the expression of immunosuppressive functions of splenic macrophages induced by Mycobacterium avium complex infection (1995) J Leukoc Biol, 58, pp. 704-712Fluhr, H., Krenzer, S., Stein, G.M., Stork, B., Deperschmidt, M., Wallwiener, D., Wesselborg, S., Licht, P., Interferongamma and tumor necrosis factor-alpha sensitize primarily resistant human endometrial stromal cells to Fas-mediated apoptosis (2007) J Cell Sci, 120, pp. 4126-4133Suk, K., Kim, S., Kim, Y.H., Kim, K.A., Chang, I., Yagita, H., Shong, M., Lee, M.S., IFN-gamma/TNF-alpha synergism as the final effector in autoimmune diabetes: A key role for STAT1/IFN regulatory factor-1 pathway in pancreatic beta cell death (2001) J Immunol, 166, pp. 4481-4489Hosseini-Moghaddam, S.M., Mousavi, A., Alavian, S.M., Is {beta} interferon a promising therapeutic option for the management of hepatitis C? (2009) J Antimicrob Chemother, 63, pp. 1097-1103Crow, M.K., Type I interferon in organ-targeted autoimmune and inflammatory diseases (2010) Arthritis Res Ther, 12 (SUPPL. 1), pp. S5Olsson, M., Nilsson, A., Oldenborg, P.A., Target cell CD47 regulates macrophage activation and erythrophagocytosis (2006) Transfus Clin Biol, 13, pp. 39-43Ishikawa-Sekigami, T., Kaneko, Y., Okazawa, H., Tomizawa, T., Okajo, J., Saito, Y., Okuzawa, C., Nojima, Y., SHPS-1 promotes the survival of circulating erythrocytes through inhibition of phagocytosis by splenic macrophages (2006) Blood, 107, pp. 341-348Jaiswal, S., Jamieson, C.H., Pang, W.W., Park, C.Y., Chao, M.P., Majeti, R., Traver, D., Weissman, I.L., CD47 is upregulated on circulating hematopoietic stem cells and leukemia cells to avoid phagocytosis (2009) Cell, 138, pp. 271-285Majeti, R., Chao, M.P., Alizadeh, A.A., Pang, W.W., Jaiswal, S., Gibbs Jr., K.D., Van Rooijen, N., Weissman, I.L., CD47 is an adverse prognostic factor and therapeutic antibody target on human acute myeloid leukemia stem cells (2009) Cell, 138, pp. 286-299Spaargaren, M., Lymphoma spread? Target CD47-SIRPa! (2011) Blood, 118, pp. 4762-4764Chao, M.P., Tang, C., Pachynski, R.K., Chin, R., Majeti, R., Weissman, I.L., Extranodal dissemination of non-Hodgkin lymphoma requires CD47 and is inhibited by anti-CD47 antibody therapy (2011) Blood, 118, pp. 4890-4901Ide, M., Ohnishi, T., Murayama, M., Matsumoto, I., Yamada, K., Iwayama, Y., Dedova, I., Yoshikawa, T., Failure to support a genetic contribution of AKT1 polymorphisms and altered AKT signaling in schizophrenia (2006) J Neurochem, 99, pp. 277-287Waern, J.M., Yuan, Q., Rurich, U., Becker, P.D., Schulze, K., Strick-Marchand, H., Huntington, N.D., Bock, M., Ectopic expression of murine CD47 minimizes macrophage rejection of human hepatocyte xenografts in immunodeficient mice (2012) Hepatology, , in press)Scalea, J., Hanecamp, I., Robson, S.C., Yamada, K., T-cellmediated immunological barriers to xenotransplantation (2012) Xenotransplantation, 19, pp. 23-30Raymond, M., Rubio, M., Fortin, G., Shalaby, K.H., Hammad, H., Lambrecht, B.N., Sarfati, M., Selective control of SIRP-alphapositive airway dendritic cell trafficking through CD47 is critical for the development of T(H)2-mediated allergic inflammation (2009) J Allergy Clin Immunol, 124, pp. 1333-42e1Verjan Garcia, N., Umemoto, E., Saito, Y., Yamasaki, M., Hata, E., Matozaki, T., Murakami, M., Miyasaka, M., SIRPa/CD172a regulates eosinophil homeostasis (2011) J Immunol, 187, pp. 2268-2277Healey, G., Veale, M.F., Sparrow, R.L., A fluorometric quantitative erythrophagocytosis assay using human THP-1 monocytic cells and PKH26-labelled red blood cells (2007) J Immunol Methods, 322, pp. 50-56Montgomery, D.C., (1991) Design And Analysis Of Experiments, , 3rd Ed. New York: John Wiley & SonsJungi, T.W., Brcic, M., Leutwyler, C., Pfister, H., Spycher, M.O., Interferon-gamma treatment impairs Fc receptor type II-mediated phagocytosis of human macrophages by a post-receptor-binding mechanism (1991) Immunology, 74, pp. 439-445Fratti, R.A., Ghannoum, M.A., Edwards Jr., J.E., Filler, S.G., Gamma interferon protects endothelial cells from damage by Candida albicans by inhibiting endothelial cell phagocytosis (1996) Infect Immun, 64, pp. 4714-4718Willenborg, D.O., Fordham, S.A., Staykova, M.A., Ramshaw, I.A., Cowden, W.B., IFN-gamma is critical to the control of murine autoimmune encephalomyelitis and regulates both in the periphery and in the target tissue: A possible role for nitric oxide (1999) J Immunol, 163, pp. 5278-5286Willenborg, D.O., Staykova, M.A., Cowden, W.B., Our shifting understanding of the role of nitric oxide in autoimmune encephalomyelitis: A review (1999) J Neuroimmunol, 100, pp. 21-35Park, H., Li, Z., Yang, X.O., Chang, S.H., Nurieva, R., Wang, Y.H., Wang, Y., Dong, C., A distinct lineage of CD4 T cells regulates tissue inflammation by producing interleukin 17 (2005) Nat Immunol, 6, pp. 1133-1141Isomi, P., Panesar, M., Annenkov, A., Clark, J.M., Foxwell, B.M., Chernajovsky, Y., Cope, A.P., Prolonged exposure of T cells to TNF down-regulates TCR zeta and expression of the TCR/CD3 complex at the cell surface (2001) J Immunol, 166, pp. 5495-5507Kassiotis, G., Kollias, G., Uncoupling the proinflammatory from the immunosuppressive properties of tumor necrosis factor (TNF) at the p55 TNF receptor level: implications for pathogenesis and therapy of autoimmune demyelination (2001) J Exp Med, 193, pp. 427-434Zakharova, M., Ziegler, H.K., Paradoxical anti-inflammatory actions of TNF-alpha: inhibition of IL-12 and IL-23 via TNF receptor 1 in macrophages and dendritic cells (2005) J Immunol, 175, pp. 5024-5033De Almeida, A.C., Barbosa, S.M., Barjas-Castro, M.D.E.L., Olalla-Saad, S.T., Condino-Neto, A., The role of glucocorticoid in SIRP alpha and SHP-1 gene expression in AIHA patients (2009) Immunopharmacol Immunotoxicol, 31, pp. 636-640Burger, P., Hilarius-Stokman, P., De Korte, D., Van Den Berg, T.K., Van Bruggen, R., CD47 functions as a molecular switch for erythrocyte phagocytosis (2012) Blood, 119, pp. 5512-5521Babic, I., Schallhorn, A., Lindberg, F.P., Jirik, F.R., SHPS-1 induces aggregation of Ba/F3 pro-B cells via an interaction with CD47 (2000) J Immunol, 164, pp. 3652-3658Tada, K., Tanaka, M., Hanayama, R., Miwa, K., Shinohara, A., Iwamatsu, A., Nagata, S., Tethering of apoptotic cells to phagocytes through binding of CD47 to Src homology 2 domain-bearing protein tyrosine phosphatase substrate-1 (2003) J Immunol, 171, pp. 5718-5726