High-potentiality preliminary selection criteria and transformation time-dependent factors analysis for establishing Epstein-Barr virus transformed human lymphoblastoid cell lines

Efficient and reliable establishment of lymphoblastoid cell lines by Epstein-Barr virus transformation from a limited amount of peripheral blood

Lymphoblastoid cell lines (LCLs) transformed by Epstein-Barr virus (EBV) serve as an unlimited resource of human genomic DNA. The protocol that is widely used to establish LCLs involves peripheral blood mononuclear cell isolation by density gradient centrifugation, however, that method requires as much as 5 ml of peripheral blood. In this study, in order to provide a more simple and efficient method for the generation of LCLs, we developed a new protocol using hemolytic reaction to enrich white blood cells for EBV transformation and found that the hemolytic protocol successfully generated LCLs from a small volume (i.e., 0.1 ml) of peripheral blood. To assess the quality of genomic DNA extracted from LCLs established by the hemolytic protocol (LCL-hemolytic), we performed single nucleotide polymorphism (SNP) microarray genotyping using the GeneChip^® 100 K Array Set (Affymetrix, Inc.). The concordances of the SNP genotyping resulting from genomic DNA from LCL-hemolytic (99.92%) were found to be as good as the technical replicate (99.90%), and Kappa statistics results confirmed the reliability. The findings of this study reveal that the hemolytic protocol is a simple and reliable method for the generation of LCLs, even from a small volume of peripheral blood.

Viable mononuclear cell stability study for implementation in a proficiency testing program: impact of shipment conditions

The impact of shipping temperatures and preservation media used during transport of either peripheral blood mononuclear cells (PBMCs) or Jurkat cells was assessed, in view of implementing of a proficiency testing scheme on mononuclear cell viability. Samples were analyzed before and after shipment at different temperatures (ambient temperature, dry ice, and liquid nitrogen) and in different preservation media (serum with cryoprotectant, commercial cryopreservation solution, and room temperature transport medium). Sample quality was assessed by viability assays (Trypan Blue dye exclusion, flow cytometry, Cell Analysis System cell counting (CASY)), and by ELISpot functional assay. The liquid nitrogen storage and shipment were found to be the most stable conditions to preserve cell viability and functionality. However, we show that alternative high quality shipment conditions for viable cells are dry ice shipment and commercial cryopreservation solution. These were also cost-efficient shipment conditions, satisfying the requirements of a proficiency testing scheme for viable mononuclear cells. Room temperature transport medium dramatically and adversely affected the integrity of mononuclear cells.

Assessment of the effect of TLR7/8, TLR9 agonists and CD40 ligand on the transformation efficiency of Epstein-Barr virus in human B lymphocytes by limiting dilution assay

Infection of human B cells with Epstein-Barr virus (EBV) induces polyclonal activation in almost all infected cells, but a small proportion of infected cells are transformed to immortalized lymphoblastoid cell lines. Since B cells are activated also by CD40 ligand (CD40L) and Toll-like receptor (TLR) agonists via a similar signaling pathway, it is likely that costimulation through these molecules could result in synergistic enhancement of the transformation efficiency of EBV. In this study, the stimulatory effect of TLR7/8 (R848), TLR9 (CpG) agonists and/or CD40L on transformation efficiency of EBV in normal human B cells was assessed using the limiting dilution assay. Costimulation of peripheral blood mononuclear cells (PBMCs) with CpG and R848, but not CD40L, increased significantly the frequency of EBV transformed B cells (p < 0.001). Neither synergistic nor additive effects were observed between TLR agonists and CD40L and also TLR7/8 and TLR9 agonists. Costimulation with R848, CpG and CD40L enhanced the proliferative response of B cells infected with EBV. This effect was more evident when enriched B cells were employed, compared to PBMCs. The promoting effect of TLR agonists stimulation, implies that EBV may take advantage of the genes induced by the TLR stimulation pathway for viral latency and oncogenesis.

CYP17A1 intron mutation causing cryptic splicing in 17α-hydroxylase deficiency

17α-hydroxylase/17, 20-lyase deficiency (17OHD) is an autosomal recessive disease causing congenital adrenal hyperplasia and a rare cause of hypertension with hypokalemia. The CYP17A1 gene mutation leads to 17OHD and its clinical features. We described an 18 y/o female with clinical features of 17α-hydroxylase/17, 20-lyase deficiency and characterized the functional consequences of an intronic CYP17A1 mutation. The coding regions and flanking intronic bases of the CYP17A1 gene were amplified by PCR and sequenced. The patient is a compound heterozygote for the previously described p.R358X and IVS1 +2T>C mutations. A first intron splice donor site mutation was re-created in minigene and full-length expression vectors. Pre-mRNA splicing of the variant CYP17A1 intron was studied in transfected cells and in a transformed lymphoblastoid cell line. When the full-length CYP17A1 gene and minigene containing the intronic mutation was expressed in transfected cells, the majority (>90%) of mRNA transcripts were incorrectly spliced. Only the p.R358X transcript was detected in the EBV-transformed lymphoblastoid cell line. The IVS1 +2T>C mutation abolished most 17α-hydroxylase/17, 20-lyase enzyme activity by aberrant mRNA splicing to an intronic pseudo-exon, causing a frame shift and early termination.

Capacity of robot handling for Epstein-Barr virus transformation

OBJECTIVES

Epstein-Barr virus (EBV) transformation has been described as a routine method to establish human B lymphoblastoid cell lines. Each established lymphoblastoid cell line represents one unique genetic information carrier and can produce unlimited quantities of DNA materials available for downstream applications and research. Undoubtedly, it is of great value to human clinical and experimental genetic studies. However, the current process of EBV transformation requires much manpower in the routine renewal of medium, which is time-consuming. This situation can become a serious problem especially when establishing a human B lymphoblastoid cell bank. A modified and cost-effective protocol for EBV transformation should be considered.

MATERIALS AND METHODS

In the present study, process in EBV transformation was modified to fit the requirements of robot handling.

RESULTS

1 mL of whole blood was demonstrated to be sufficient to perform EBV transformation. Additionally, EBV transformation can performed in 96-deep-well plates that are directly and widely used with automatic work platforms.

CONCLUSIONS

Based on these facts, a process of EBV transformation can be modified to fit the requirements of robot handling.

Generation of Epstein-Barr Virus (EBV)-immortalized B cell lines

Immortalization of B lymphocytes by EBV is an effective procedure for inducing long-term growth of certain human B lymphocytes. The protocol described in this unit to accomplish this can be divided into three stages: preparation of virus, preparation of target cells to be immortalized, and EBV infection and growth of infected cells.