International Journal of Advanced Biological and Biomedical Research Available online at http:www.ijabbr.com Volume 8, Issue 4 (2020) pp. 429-439 DOI: 10.33945/SAMI/IJABBR.2020.1.8 429 | Page Original Article Diverse Cytotoxic Capability of Silver Nanoparticles against the Normal and Cancerous Lymphocytes Niloufar Gholamkhasi, Nastaran Asghari Moghaddam * , Azadeh Mohammadgholi Department of Biology, Central Tehran Branch, Islamic Azad University, Tehran, Iran *Corresponding Author E-mail: nas.asgharimoghaddam@iauctb.ac.ir Received: 30 April 2020, Revised: 09 June 2020, Accepted: 24 June 2020 ABSTRACT Despite the toxic effects on numerous organs, silver nanoparticles can be used to cease cell cycle and promotes apoptosis in cancerous cells. Therefore, by choosing the right dosage nanoparticles can be effective in cancer treatment, whilst do not harm normal tissues. In the current study, it has been tried to measure silver nanoparticles toxicity against HPB-ALL leukemia cell line and normal human lymphocytes. The cytotoxicity of 20-nanometer silver nanoparticles was investigated by MTT test. Also, nanoparticles effect on apoptosis was assessed by flow cytometry. DNA fragmentation analysis was done to investigate the genotoxicity. MTT colorimetric assay revealed that the maximal half inhibitory concentration (IC50) of silver nanoparticles were at 8.43 µg/mL and 15.74 µg/mL in cancer cell-line and normal cells, respectively, at 24-hour exposure. The IC50 doses of silver nanoparticles were used to assess the induction of apoptosis by flow cytometry. The apoptosis occurred in 12.34% of normal cells and 36.88% of HPB-ALL cells. The difference between these two groups were statistically significant (P<0.0001). Besides, the size and the complexity of cancer cells treated by nanoparticles decreased more than normal cells. The obtained IC50 doses were used for genotoxicity assay, too. The DNA fragmentation results were in accordance with cytotoxicity results and showed more fragmentation in cancer cells. It could be concluded that the nanoparticles of silver showed lower toxicity to normal lymphocytes in comparison to leukemia HPB-ALL cell-line. Hence, it may be useful to concern it as a potential chemotherapeutic agent having lowered side effects in cancer therapy. Key words: Leukemia, Silver nanoparticles, Cytotoxicity Introduction Acute leukemia is diagnosed by reducing hematopoietic elements and accumulation of immature cells (blasts). According to the lineage origin, two major leukemia can be distinguished: acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL) (Bodet-Milin et al., 2016). ALL is a malignancy caused by the irrepressible proliferation of lymphoid progenitor cells from bone marrow, blood and extra-medullary sites