Spleen distribution and serum immune responses after acute administration of silica-conjugated magnetite (Fe3O4) nanoparticles

Cytokine storm is characterized by increased levels of proinflammatory cytokines. Magnetic nanoparticles (MNPs)-conjugated antibody therapy is promising in treating cytokine storms. This study will evaluate the time-dependent distribution of the silica-coated MNP (MNP-Si) in the spleen and consequent serum cytokine changes for 30 days. MNP-Si were administered to female BALB/c mice via the tail vein injection. The distribution of Fe in the spleen tissue was analyzed by ICP-MS both in control and MNP-Si-treated mice. Moreover, the acute immune toxicity in serum was investigated by analyzing IFN-gamma and IL-6 levels. Fe in the control spleen is 0.98 x 10(6) mu g/mg of dry weight. The highest average concentration of Fe in the spleen was measured on day 10 (1.4 x 10(6) mu g/mg). And at day 30, Fe levels decreased to 1.0 x 10(6) mu g/mg. IFN-gamma levels significantly increase to a maximum on day 6 and remain elevated until day 30. IL-6 levels are not elevated after MNP-Si administration. Although the cytokines in tissue homogenates were elevated at day 20, the data are statistically non-significant. In conclusion, the proinflammatory cytokine IFN-gamma levels were increased on day 6, indicating induced activation of macrophages and systemic inflammation after MNP-Si administration. Therefore, the dose and composition of the MNP-Si should be revised for potential usage for therapeutic purposes.