For the study, 20 ml of blood were drawn in EDTA coated-tubes for each subjects. PBMC (whole mononuclear cells from peripheral blood) and T cell isolation procedures were adapted from Current Protocols in Immunology (1997, sections 7.1 and 7.5.1–7.5.11). Briefly, PBMC isolation was done by centrifugation with Ficoll-Paque (GE healthcare, Mississauga, Canada) and washed twice with HBSS (Hanks balanced salt solution, GIBCO, Burlington, Canada). T cells were isolated from the PBMCs by immunomagnetic isolation using CD3 dynabeads (Invitrogen (Dynal Biotech), Burlington, Canada). The beads were washed 3 times and incubated with the PBMCs for 45 min on a rotator at 4°C. Coated CD3+ cells with the dynabeads were isolated using a strong magnet (Steam Cell Technology) and washed 5 times with PBS/FBS. CD3+ cells coated with the dynabeads were then frozen at −80°C until DNA extraction. To isolate monocyte cells, B cells were extracted away from the remaining PBMC with CD9 dynabeads (Invitrogen (Dynal Biotech), Burlington, Canada) following the same procedure as for T cells isolation and then frozen at −80°C until DNA extraction. Monocytes and T cells DNA was extracted with Wizard® Genomic DNA Purification kit (Promega, Madison, United States) following the manufacturer’s protocol.
