Background Graphene oxide (GO) is a promising nanomaterial for potential application in the versatile field of biomedicine. Graphene-based nanomaterials have been reported to modulate the functionality of immune cells in culture and to induce pulmonary inflammation in mice. Evidence pertaining to the interaction between graphene-based nanomaterials and the immune system in vivo remains scarce. The present study investigated the effect of polyethylene glycol-coated GO (PEG-GO) on antigen-specific immunity in vivo. Methods BALB/c mice were intravenously administered with a single dose of PEG-GO (0.5 or 1 mg/kg) 1 hour before ovalbumin (OVA) sensitization, and antigen-specific antibody production and splenocyte reactivity were measured 7 days later. Results Exposure to PEG-GO significantly attenuated the serum level of OVA-specific immunoglobulin E. The production of interferon-γ and interleukin-4 by splenocytes restimulated with OVA in culture was enhanced by treatment with PEG-GO. In addition, PEG-GO augmented the metabolic activity of splenocytes restimulated with OVA but not with the T-cell mitogen concanavalin A. Conclusion Collectively, these results demonstrate that systemic exposure to PEG-GO modulates several aspects of antigen-specific immune responses, including the serum production of immunoglobulin E and T-cell functionality.

Hispolon is an active ingredient contained in the medicinal mushroom Phellinus linteus (PL) that is used in traditional Chinese medicine for various remedies, including lymphatic diseases. Previous studies reported that hispolon exhibited anti-inflammatory activities and suppressed mitogen-induced proliferation of splenic lymphocytes. It remains unclear if hispolon influences antigen-specific immunity. The present study investigated the effects of hispolon on cytokine production by antigen-activated T cells. Ovalbumin (OVA)-primed splenocytes were exposed to hispolon, followed by restimulation with OVA. Cell viability was determined by the AlamarBlue® assay and T cell cytokine production was measured by enzyme linked immunosorbent assay (ELISA). The splenocyte viability and the production of interleukin (IL)-4 were unaffected, whereas the production of interferon (IFN)-γ was significantly suppressed by treatment with hispolon (1–5 μM) in a concentration-dependent manner. The suppressive effect of hispolon on the production of IFN-γ was attenuated in the presence of thiol antioxidants, including N-acetyl-L-cysteine (NAC) and glutathione, whereas the non-thiol antioxidant pyruvate was ineffective. Taken together, these results demonstrated that hispolon induced a differential effect on antigen-induced cytokine production by T cells, in which the T helper 1 (Th1) cytokine IFN-γ was sensitive, whereas the Th2 cytokine IL-4 was unaffected. In addition, the suppressive effect of hispolon on IFN-γ production was associated with the diminishment of intracellular glutathione.