by Epimakhova E.V. | Ermakov E.A. | Kazantseva D.V. | Smirnova L.P. | Mental Health Research Institute,
Tomsk National Research Medical Center, Russian Academy of Sciences, Tomsk, Russia | Institute of
Chemical Biology and Fundamental Medicine, Laboratory of Repair Enzymes, Novosibirsk, Russia
Background: DNA-hydrolyzing catalytic IgGs have cytotoxic effects in autoimmune
diseases [Sabirzyanova A.Z. et.al., 2013; Nevinsky G.A., 2017]. Such IgG antibodies are
capable to transgress the cell membrane, influence intracellular processes, and activate cell
death processes [Rivadeneyra-Espinoza L. et.al, 2006]. Recently, DNA-hydrolyzing IgGs
have been discovered in schizophrenia [Ermakov E.A. et.al., 2015].
The aim of the study was to investigate the effects of IgG isolated from the serum of
schizophrenic patients with DNA-hydrolyzing activity on cell viability of the SH-SY5Y human
neuroblastoma cell line.
Methods: Serum of 8 patients with paranoid schizophrenia in the acute phase and 7 healthy
persons matched by sex and age was used. IgG was purified from serum by affinity
chromatography on Protein-G-Sepharose columns. The homogeneity of the preparations was
confirmed by the method of gradient electrophoresis in 12.5% PAGE. The DNA hydrolyzing
activity of IgG was assessed by the degree of hydrolysis of the pBluescript plasmid. The cell
viability of the SH-SY5Y cell line after exposure to purified IgG preparations was assessed
by high-throughput screening on the CellInsight CX7 platform (Thermo Scientific, USA)
using the fluorescent dyes propidium iodide and Hoechst. The final antibody concentration
was 0,1 and 0,2 mg / ml. Statistical analysis was performed using the SPSS software,
release 20.0, for Windows.
Results: Of the 8 IgG preparation obtained, 4 drugs had high DNA-hydrolyzing activity. All
tested IgG preparations from healthy donors were inactive. One-way ANOVA analysis after
exposure to antibodies (0.1 mg/ml) showed no significant differences in the proportion of
dead cells (p=0.688 after 24 hours). Similar results were obtained at a higher concentration
of antibodies – 0.2 mg/ml.
Conclusions: Thus, it has been shown in vitro that IgGs isolated from the serum of
schizophrenia patients with or without DNA-hydrolyzing activity does not exhibit cytotoxic properties against the SH-SY5Y human neuroblastoma cell line.