REDOX REGULATION OF B CELL ACTIVATION AND THE ANTI-VIRAL HUMORAL IMMUNE RESPONSE

Reactive oxygen intermediates (ROI) are often regarded as toxic byproducts whose uncontrolled production induces oxidative stress damaging macromolecules and have been implicated in a wide variety of disorders. However, recent studies suggest that ROI facilitate normal cellular physiology by acting as secondary messengers generated following receptor ligation. Our understanding of the role of these molecules during the humoral immune response, the oxidation events that modulate B cell signaling, and their contribution to B cell activation is limited. Therefore, we have examined the importance of the reversible formation of cysteine sulfenic acid on B cell activation and proliferation. BCR ligation with anti-IgM or antigen resulted in ROI production that reaches a maximum by 15 minutes. Increased ROI coincides with elevated levels of the first oxidation product of cysteine, sulfenic acid, in the total proteome. Analysis of specific proteins revealed that the protein tyrosine phosphatases SHP-1, SHP-2, and PTEN were modified to cysteine sulfenic acid following B cell activation. Using 5,5-dimethyl-1,3-cyclohexanedione (dimedone), a compound that covalently reacts with sulfenic acid to prevent its further oxidation or reduction, we examined the contribution of reversible cysteine sulfenic acid formation to B cell activation, proliferation, and differentiation. We found incubation with dimedone results in a concentration dependent block in cell division induced by anti-IgM. Although early tyrosine phosphorylation events are initiated following anti-IgM incubation, the reduced proliferation of dimedone pre-treated cultures appeared to be due to the inhibition of capacitative calcium entry. Because we identified a critical role for ROI and the oxidative modification cysteine sulfenic acid during B cell activation, we assessed the importance of these molecules to the humoral immune response. This was accomplished by treating lymphocytic choriomeningitis virus (LCMV) infected mice with Mn(III)tetrakis(4-benzoic acid)porphyrin chloride (MnTBAP), a superoxide dismutase mimetic, from days 0-8 postinfection. On day 8 postinfection, splenic LCMV specific IgM and IgG antibody secreting cells (ASC) were 22- and 457-fold lower in MnTBAP-treated mice, respectively. However, by day 38 post infection, LCMV specific IgG ASC were decreased 5-fold in the bone marrow. In contrast, the number of LCMV specific memory B cells was unaffected. In addition to decreases in ASC, MnTBAP treatment decreased the number of functional virus-specific CD4+ T cells. The decreased number of ASC observed on day 8 in drug-treated mice were due to a combination of Bim-mediated cell death and decreased proliferation. Together, these data demonstrate that ROI regulate antiviral ASC expansion and have important implications for understanding the effects of antioxidants on humoral immunity during infection and immunization. Collectively, this work provides insight into the importance of ROI during B cell responses and has implications in the design of effective vaccines and therapeutics.

Grantor dc:publisher

Wake Forest University

Year dc:date.issued

2012

Author dc:creator

• Crump, Katie E

• Antibody Secreting Plasma Cells

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/10339/37647

OAI identifier oai:identifier

oai:wakespace.lib.wfu.edu:10339/37647