Delayed processing of blood increases the frequency of activated CD11b+ CD15+ granulocytes which inhibit T cell function

Isolation and preservation of peripheral blood mononuclear cells for analysis of islet antigen-reactive T cell responses: position statement of the T-Cell Workshop Committee of the Immunology of Diabetes Society

“…Both granulocyte contamination and inhibition of T cell responses were effectively limited when granulocyte activation was reduced by diluting blood in phosphate-buffered saline (PBS) or RPMI-1640 (1:1) prior to storage [23,29]. Similar observations were made in a macaque study, in which granulocyte contamination affected the quality and quantity of spots in IFN-g ELISPOT assays [30].…”

“…To a lesser extent, this is also true for fresh PBMC preparations, and is associated with increased granulocyte contamination [29]. In the study by Bull and colleagues [24], blood samples were either stored for less than 8 h or for 24 h before PBMC isolation and cryopreservation.…”

Persistence of Th1/Tc1 responses one year after tetravalent dengue vaccination in adults and adolescents in Singapore

“…This required that a laboratory close to the clinical site perform the stimulation of whole blood samples and freshly purified PBMCs, which in turn required that samples be collected in the morning to allow fresh blood to be simulated for 5 h. Due to school, morning study visits proved unfeasible for adolescents and instead adolescent participants were recruited in the afternoon and samples were processed the next day. While this limits the validity of comparing results between age groups as it may have contributed to the lower responses observed in adolescents compared with adults, 21,22 it did not prevent us from demonstrating the feasibility of performing these assays with just 6 mL of blood.…”

Validation of Increased Blood Storage Times with the T-SPOT. TB Assay with T-Cell Xtend Reagent in Individuals with Different Tuberculosis Risk Factors

“…Activated granulocytes are responsible for inhibiting T cells, principally mediated by the release of H 2 O 2 (6, 9), leading to reduced cytokine release by effector T cells (7). These effects may contribute to the observed reduced clinical sensitivity of both IGRAs when performed on stored blood without the removal of granulocytes (2,3,8,10).…”