BTLA expression on resting Vγ9Vδ2 T cells from HV. (A) Multiparametric flow cytometry analysis of B7/CD28 family members’ expression on peripheral γδ T cells (CD3⁺TCRVγ9⁺) gated from HV PBMC (n = 8). (B) Expression of BTLA on CD4+ and CD8+ αβ T cells and B cells (n = 4). (C) Gating strategy for BTLA expression on γδ T cells’ differentiation subsets by flow cytometry. γδ T cells were analyzed for CD45RA and CD27 expression, resulting in the following subsets of γδ T lymphocytes: naïve (CD45RA⁺CD27⁺), CM (CD45RA⁻CD27⁺), EM (CD45RA⁻CD27⁻), and TEMRA (CD45RA⁺CD27⁻). (D) Representative histograms of BTLA expression in γδ T-cell differentiation subsets. γδ T cells from PBMCs of HV (n = 4) were analyzed by flow cytometry for BTLA expression according to differentiation subsets. MFI, mean fluorescence intensity.