Abstract
Colloidal silver (AgC) is currently used by humans and it can be internalized through inhalation, injection, ingestion, and dermal contact. However, there is limited information about immunological activity; more investigations using colloidal silver are needed. In the present study, the effects of AgC (17.5 ng/mL) on immunological parameters (proliferation and immunophenotyping) using human peripheral blood mononuclear cells (PBMC) and macrophages (phagocytosis) and cytotoxicity on leukemia and lymphoma cancer cell lines (1.75 to 17.5 ng/mL) were investigated. AgC was observed to significantly (p<0.05) decrease interleukin-2 (IL-2) production and proliferation induced by phytohemagglutinin or concanavalin A in PBMC without affecting its cell viability but with cytotoxic effect on cancer cells. IL-2, IL-4, IL-6, IL-10, INF-γ, and IL-17A cytokines production and CD3+, CD3−CD19+, CD3+CD4+, CD3+CD8+, and CD16+CD56+ PBMC phenotypes were not affected by AgC. The present study demonstrates that colloidal silver is harmless and nontoxic to the immune system cells and its ability to interfere with the immune response by decreasing cell proliferation when stimulated with mitogens demonstrated the antilymphoproliferative potential of AgC.
Highlights
Bioactivity of substances has been screened to identify properties related to the antitumoral or antiproliferative action [1]
Silver ions are more toxic because they can interact with negative groups of proteins, producing structural changes on the cellular membrane and cytoplasmic proteins, while AgNPs can interact with DNA, causing damage and structural blocking; some studies have proposed that these nanostructures can produce increased toxicity at long exposition times due to the fact that AgNPs in aqueous solutions can oxidize and release silver ions; the successful use of colloidal silver solutions can be explained by this action mechanism [6, 7]
The anticancer activity of AgC on MCF-7 cancer cells is probably due to induced apoptosis by decreasing lactate dehydrogenase and increasing superoxide dismutase activities; in contrast, in peripheral blood mononuclear cells (PBMC), lactate dehydrogenase activity decreased with AgC, but it did not correlate with cell death [3]
Summary
Bioactivity of substances has been screened to identify properties related to the antitumoral or antiproliferative action [1] Products with this activity have been used in clinical practice for the treatment of cancer or diseases related to inflammation such as autoimmunity. Since 1964, colloidal silver (AgC) has been registered as a biocidal material in the United States [2]; in Mexico, AgC is commonly used as disinfectant of water and food for human consumption [3]. These products are a mix of metallic nanoparticles with oxidation state of zero (Ag+0) and silver salts with oxidation states of Ag+1, +2, or +3 [4]. There is scarce scientific information about immunological and cancer parameters in humans regarding the effects of colloidal silver, as a mix of nanoparticles and ions, compared to silver nanoparticles
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