Assessing the Impact of Cell Isolation Method on B cell Gene Expression using Next-Generation Sequencing

Transcriptional profiling of PBMCs is a widely explored research approach across multiple fields. Cell populations of interest are generally isolated prior to analysis, especially if low frequency cell populations are desired. B cells, in particular, make up approximately 5-10% of total PBMCs in healthy individuals, thus, isolation of B cell populations is crucial for researchers investigating B cell malignancies. The most widely used cell isolation methods include negative or positive magnetic cell sorting (MCS) and fluorescence-activated cell sorting (FACS). In contrast to negative MCS, it is widely believed that positive MCS and FACS may affect gene expression due to the direct interaction of cell selection antibodies with surface markers. To the best of our knowledge, no specific studies have examined these effects within CD19+ B cell populations. To evaluate this, we have performed RNA-seq on B cells isolated from n=4 healthy donors using three distinct methods: positive and negative MCS using the EasySep StemCell Technologies kits and FACS, performed using the MACSQuant Tyto sorter (Miltenyi Biotec). We report significant gene expression changes following CD19-dependent B cell isolation via either positive MCS or FACS relative to negative MCS, including a general upregulation of genes associated with immune activity and receptor signaling and downregulation of RNA processing genes. These results suggest B cell isolation methods should be taken into consideration when designing experiments or incorporating publicly available sequencing datasets into ongoing research studies, as they may significantly impact the reliability and interpretability of the findings. Overall design: Primary human B cells were isolated from whole blood of n=4 healthy donors via 3 different methods: positive MCS isolation, negative MCS isolation, and FACS. RNA-seq was performed on matched samples to evaluate impact isolation method has on gene expression.