Expression of costimulatory ligands and receptors on γδ T lymphocytes and NK cells. (A) Fresh γδT lymphocytes from healthy donors (top histograms) or γδT lymphocytes expanded in the presence of IPP+IL-2 (bottom histograms) were stained with mAbs specific for CD80, CD86, CD252 (OX40L) and CD137L (41BBL). The expression of indicated costimulatory ligands on gated CD3⁺γδTCR⁺ cells is shown. (B) NK cells cultured with media alone or immobilized hIgG1 with or without in vitro expanded γδ T lymphocytes for 48 hours were stained with mAbs specific for CD28, CD152 (CTLA-4), CD134 (OX40), and CD137 (4-1BB). Overlays of histograms representing gated CD3⁻CD56⁺ NK cells are shown. Depicted data represent 1 of 5 independent experiments.