Figure 2.

NK cell hyporesponsiveness in tumor or infection contexts. (a) When tested in vitro for their cytolytic function, NK cells from healthy donors are able to kill virally infected or tumor cells (red bold arrow). In contrast, peripheral blood NK cells from virally infected patients or intratumoral NK cells from tumor-bearing patients have lower expression of activating receptors and a decreased ability to degranulate and to produce IFNγ or TNFα (impaired cytotoxicity, red unbold arrow). (b) During a second exposure to target cells, NK cells from healthy donors, become hyporesponsive with shared features with NK cells from virally infected or tumor-bearing patients (i.e., decreased expression of activating receptor, decreased degranulation and decreased production of IFNγ, TNFα). (c) Treatments with cytokines have been shown to restore NK cell functionality in both cases.