Phenotypic characterization of γδ T cells mobilized in response to acute psychological stress

Gamma-delta (γδ) T lymphocytes are versatile cells that play key roles in bacterial clearance, wound repair, and delayed-type hypersensitivity reactions. Recently we showed that these cells are mobilized into the blood during acute psychological stress. γδ T lymphocytes are a heterogeneous population of cells, and the current study aimed to characterize the effects of stress on distinct γδ T cell populations.Twenty-nine healthy participants completed a 12 min speech task. Blood samples were taken after a resting baseline, during the last two minutes of the task, and after a 15 min recovery period. Flow cytometry was used to investigate the response of memory phenotypes (i.e. Naïve, Central memory, Effector Memory, and CD45RA+ Effector Memory (EMRA)) within the δ1 and δ2 γδ T cell populations. Cells were further analysed on expression of adhesion molecules (CD11a, CD62L) and the NK-receptor CD94.Both the δ1 and δ2 subsets were mobilized during stress, and for both subsets, EMRA cells were mobilized to a much greater extent than the other memory phenotypes. Analysis of migration markers revealed that mobilized cells had a predominantly tissue migrating phenotype (CD11ahiCD62Llo/neg) and expressed high levels of the NK-receptor CD94.The current findings indicate that stress primarily mobilizes γδ memory cells that have high cytotoxic capability, tissue homing potential, and the capacity for rapid, innate-like target recognition. This selective mobilization possibly provides protection in contexts when tissue damage and antigen exposure are more likely to occur.