MHC Class II Activation and Interferon-γ Mediate the Inhibition of Neutrophils and Eosinophils by Staphylococcal Enterotoxin Type A (SEA)

• Published in: Frontiers in cellular and infection microbiology Vol. 7; p. 518
• Main Authors: Ferreira-Duarte, Ana P, Pinheiro-Torres, Anelize S, Anhê, Gabriel F, Condino-Neto, Antônio, Antunes, Edson, DeSouza, Ivani A
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 13.12.2017
• Subjects: adhesion; Animals; bone marrow; Cell Adhesion - drug effects; Cells, Cultured; chemotaxis; Chemotaxis - drug effects; Enterotoxins - metabolism; Eosinophils - drug effects; Eosinophils - immunology; eotaxin; Histocompatibility Antigens Class II - metabolism; Immune Tolerance; Interferon-gamma - metabolism; interleukin-8; Mice, Inbred BALB C; Microbiology; Neutrophils - drug effects; Neutrophils - immunology; eotaxin; adhesion; interleukin-8; bone marrow; chemotaxis
• ISSN: 2235-2988; 2235-2988
• DOI: 10.3389/fcimb.2017.00518

Staphylococcal enterotoxins are classified as superantigens that act by linking T-cell receptor with MHC class II molecules, which are expressed on classical antigen-presenting cells (APC). Evidence shows that MHC class II is also expressed in neutrophils and eosinophils. This study aimed to investigate the role of MHC class II and IFN-γ on chemotactic and adhesion properties of neutrophils and eosinophils after incubation with SEA. Bone marrow (BM) cells obtained from BALB/c mice were resuspended in culture medium, and incubated with SEA (3-30 ng/ml; 1-4 h), after which chemotaxis and adhesion were evaluated. Incubation with SEA significantly reduced the chemotactic and adhesive responses in BM neutrophils activated with IL-8 (200 ng/ml). Likewise, SEA significantly reduced the chemotactic and adhesive responses of BM eosinophils activated with eotaxin (300 ng/ml). The inhibitory effects of SEA on cell chemotaxis and adhesion were fully prevented by prior incubation with an anti-MHC class II blocking antibody (2 μg/ml). SEA also significantly reduced the intracellular Ca levels in IL-8- and eotaxin-activated BM cells. No alterations of MAC-1, VLA4, and LFA-1α expressions were observed after SEA incubation. In addition, SEA elevated by 3.5-fold ( < 0.05) the INF-γ levels in BM cells. Incubation of BM leukocytes with IFN-γ (10 ng/ml, 2 h) reduced both neutrophil and eosinophil chemotaxis and adhesion, which were prevented by prior incubation with anti-MHC class II antibody (2 μg/ml). In conclusion, SEA inhibits neutrophil and eosinophil by MHC class II-dependent mechanism, which may be modulated by concomitant release of IFN-γ.