RNAi Transfection Optimized in Primary Naïve B Cells for the Targeted Analysis of Human Plasma Cell Differentiation

Authors:
Shih T, De S, Barnes BJ
In:
Source: Frontiers in Immunology
Publication Date: (2019)
Issue: 10: 1652
Research Area:
Immunotherapy / Hematology
Cells used in publication:
B cell, human
Species: human
Tissue Origin: blood
Platform:
4D-Nucleofector® X-Unit
Experiment

Isolated naïve B cells were centrifuged in antibiotic-free, serumcontaining media as recommended by the Amaxa P3 Primary Cell 4D-Nucloefector X Kit L [Lonza, Cologne, Germany, V4XP-3024] at 300 × g for 10min at room temperature. Cells were resuspended in room temperature Amaxa buffer as suggested by the manufacturer for primary cells. 2–3 × 10^6 cells/100 µL cuvette was the final concentration of cells used for nucleofection.B cells were nucleofected with either mock (no siRNA), 1.5µM of ON-TARGETplus Non-targeting Control Pool [Dharmacon, Lafayette, CO, D-001810-10-05] or SMARTpool ON-TARGETplus human IRF4 siRNA [Dharmacon, LU-019668-00-0005]. 1–1.5µM ON-TARGETplus Targeted Control GAPD Pool [Dharmacon, D-001830-10-05], 1–1.5µM of ON-TARGETplus AICDA siRNA [Dharmacon, LU-021409-00-0005], and 1.5µM siGLO green transfection indicator siRNA [Dharmacon, D- 001630-01-05] were also used. Cells were nucleofected using program EO-117 for primary human B cells of the Amaxa 4D Nucleofector system [Lonza] composed of the core unit and the X unit.

Abstract

Upon antigen recognition, naïve B cells undergo rapid proliferation followed by differentiation to specialized antibody secreting cells (ASCs), called plasma cells. Increased circulating plasma cells are reported in patients with B cell-associated malignancies, chronic graft-vs.-host disease, and autoimmune disorders. Our aim was to optimize an RNAi-based method that efficiently and reproducibly knocks-down genes of interest in human primary peripheral B cells for the targeted analysis of ASC differentiation. The unique contributions of transcriptional diversity in species-specific regulatory networks and the mechanisms of gene function need to be approached directly in human B cells with tools to hone our basic inferences from animal models to human biology. To date, methods for gene knockdown in human primary B cells, which tend to be more refractory to transfection than immortalized B cell lines, have been limited by losses in cell viability and ineffective penetrance. Our single-step siRNA nucleofector-based approach for human primary naïve B cells demonstrates reproducible knockdown efficiency (~40-60%). We focused on genes already known to play key roles in murine ASC differentiation, such as interferon regulatory factor 4 (IRF4) and AID. This study reports a validated non-viral method of siRNA delivery into human primary B cells that can be applied to study gene regulatory networks that control human ASC differentiation.