Inherited PD-1 deficiency: single-cell RNA sequencing (scRNASeq) of PBMCs

Abstract

To identify transcriptional modules perturbed by inherited PD-1 deficiency, single-cell RNA sequencing was performed on PBMCs obtained from the ten-year-old PD-1-deficient patient and his healthy six-year-old brother (wild-type for the PDCD1 allele). The preparation was enriched in viable cells by resuspending 1×10^6 cells in 200 μL of 2% FBS and 1 mM calcium chloride in PBS and passing the suspension through a strainer with 40 µm pores, before removing dead cells with the EasySep Dead Cell Removal Kit (StemCell Technologies, Cat: 17899). The initial viability of ~50% was increased to 79% and 75% for the samples of the patient and his brother, respectively. The samples were loaded onto a 10X Genomics Chromium chip for single-cell capture. Libraries were prepared with the Chromium Single Cell 3’ Reagent Kit (v3.1). Library quality was assessed with a Bioanalyzer DNA chip. The libraries were sequenced on one lane (S4 flowcell) of an Illumina NovaSeq 6000 sequencer. Sequences were processed with Cell Ranger 3.1.0. The filtered feature-cell matrix was used for subsequent analyses. Separately, PBMCs from four healthy controls were processed and sequenced as described above (i.e., historical controls), and the data were analyzed simultaneously. Publicly available control PBMC datasets were downloaded from the 10X Genomics website (https://support.10xgenomics.com/single-cell-gene-expression/datasets). The filtered feature-cell matrix was retrieved for the following datasets: frozen PBMCs (Donors A to C) from Zheng et al.64, 33,000 PBMCs from a healthy donor from the Chromium demonstration (v1 Chemistry, processed by Cell Ranger 1.1.0), 8,000 PBMCs from a healthy donor from the Chromium demonstration (v2 Chemistry, processed by Cell Ranger 2.1.0), 10,000 PBMCs from a healthy donor from the Chromium demonstration (v3 Chemistry, processed by Cell Ranger 3.0.0) with or without cell surface protein levels determined by TotalSeq, 5,000 PBMCs from a healthy donor from the Chromium Next GEM demonstration (v3.1 Chemistry, processed by Cell Ranger 3.0.2) with or without cell surface protein levels determined by TotalSeq, and a total of 66,000 PBMCs from an aggregate of eight Chromium connect channels and eight manual channels (v3.1 Chemistry, processed by Cell Ranger 3.1.0). These 10 datasets were used as the baseline for subsequent analyses