Isolation Of Blood Components From Mixed Sample By Immunomagnetic Beads

Objective:The purpose of this study is to use immunomagnetic beads method to separate blood components(leukocytes)from mixed samples and to eliminate or reduce the interference of blood-derived STR typing in mixed samples on the analysis of results.And the factors affecting the effect of the scheme and the applicable types of samples are explored.Methods:1 To explore the effect of mixing ratio on the sorting effect of immunomagnetic beads.Taking the mixed sample of oral exfoliated epithelial cells and fresh blood as the model,the improvement of STR map of the sample after sorting was observed and analyzed compared with the control group without sorting by changing the mixing ratio of the two components.Among them,the control group and the experimental group should ensure that the cell content of each component is roughly the same,by first preparing the cell suspension,and then taking the same volume of cell suspension in the control group and the experimental group.The improvement of the atlas of the experimental group and the control group was analyzed by intuitive comparative observation.(2)To explore the influence of time factors on the sorting effect of immunomagnetic beads.First,fresh blood was stored at room temperature for 0-2.5hours(0h,0.5h,1h,1.5h,2h,2.5h)and then mixed with oral exfoliated epithelial cells to prepare mixed samples.The experimental group and the control group were also set up.The STR patterns of the samples in the experimental group were compared with those of the control group.(3)To explore the feasibility of using immunomagnetic beads method to separate blood components(leukocytes)from blood and semen,blood and hand exfoliated cells.To explore the improvement of the STR map of these two kinds of mixed samples compared with the unsorted control group,the experimental method is similar to method(1)and(2).Results:1 The immunomagnetic beads method can effectively separate the blood components(white blood cells)in the mixed samples,and improve the mixed STR pattern obviously.When the proportion of blood in the sample was relatively low,the control group was mixed STR typing,and after immunomagnetic beads sorting,the experimental group was similar to single source STR typing;when the blood proportion was relatively high,the control group was mixed STR typing,but the peak height of STR typing band derived from oral exfoliated epithelial cells was low or even lost.After immunomagnetic beads sorting,the experimental group was still STR mixed typing,but the STR typing band from oral exfoliated epithelial cells became the main peak.When the oral exfoliated epithelial cells in the mixed samples were small and the blood accounted for a large proportion,the control group was the result of single STR typing derived from blood.After immunomagnetic beads sorting,the experimental group was STR mixed typing,including all alleles derived from oral exfoliated epithelial cells.2 With the prolongation of the placement time of blood samples,the sample map quality of the experimental group decreased gradually after 0-2.5 h separation.The maps of 0h,0.5h,1h and 1.5h groups were improved better after magnetic beads separation,while the STR patterns of samples were still mixed after 2h and 2.5h separation.3 After the mixed samples of semen and blood were sorted by immunomagnetic beads,the STR map of semen and blood was significantly better than that of the control group.4 After the mixed samples of hand exfoliated cells and blood were sorted by immunomagnetic beads,the peak height and area of STR allele of blood donors in the experimental group were significantly lower than those in the control group,but no allele typing of exfoliated cells was detected.Conclusion:Immunomagnetic beads method can be used to separate blood components in mixed samples,which can greatly improve the mixed STR patterns,which provides a new idea for the treatment of mixed samples in forensic laboratories,but this method is greatly affected by time factors and is difficult to be used to treat mixed samples of blood and exfoliated cells of the hand.