Thymic stromal lymphopoietin augments the cytolytic activity of the human natural killer cell line NK-92

Culturing the human natural killer cell line NK-92 for 24 h in the presence of thymic stromal lymphopoietin (TSLP) potentiated its cytotoxic capacity against the erythroleukemia cell line K562. Longer incubation times did not augment the NK activity any further. No synergistic effects with respect to either proliferation or cytotoxicity were observed when TSLP was mixed with suboptimal concentrations of IL-2. FACS analysis of the NK-92 cells indicated expression of TSLPR but not the other component of the TSLP receptor complex, namely IL-7R alpha. Some of the surface molecules known to be involved in NK cell-mediated cytotoxicity were also monitored. None of the receptors analyzed altered their expression to any major extent upon culture in TSLP or IL-2. However, a limited number of NK-92 cells were observed that had a rather low CD94/NKG2A expression, which increased upon stimulation with TSLP or IL-2.